I frequently get asked for advice on computer purchase decisions. The first and most important answer is that everyone's needs and interests are different so there's no one size fits all. However, I've not been shy about sharing what my thoughts have been, for my own decisions. I've purchased 5 MacBooks and 12 Macs over the last 15 years (including ones I've purchased for a use at the church I worked at). Right now, I feel pretty clear in my preferences and reasons regarding my MacBook needs especially. A friend recently asked me for my opinions with a series of what I deemed to be good and thoughtful questions. So, I thought I would post my answers publicly as well.
"What MacBook model do you suggest?"
I think the 13" base MacBook Pro is the best portable computer value ever, absolutely ever. I do like large screens (my iMac at home is a large screen), but I think the size disadvantage of the 15" or larger portable is simply not worth it. I wrote my dissertation mainly on my 13" MacBook, and its has multiple wide columned tables. Basically, it still accommodated my needs; with two-finger scrolling, screen accessibility is just so natural. I'm certain there are some niche uses where they need a larger screen, but for someone who takes the computer from home to the office every day, there's no question about it. The unibody design is absolutely fantastic, a huge step over the white plastic case MacBook still selling.
The way I encourage anyone to figure out which MacBook meets their needs is to consider the different base configuration using this table and then ask themselves, what am I gaining for the price increase and do I need/want that?
As far as configuration, the first add-on I spend for would be faster processor speed. Hard-drive can be upgraded later and unless you're doing video editing or loading tons of [legally?] downloaded movies and music, you're not going to need more. RAM can be added later, and more cheaply via third party.
Computers get a speed bump in their specs every year or two. It is always a good idea to not buy if you can wait a month if a new release is pending in the next month or so, but short of that, I'd say buy when you want/need/can afford it. You can look this site to gauge if a new update is coming soon, or ask your Mac friends about it.
"Is getting the Air with its portability worth the high cost?"
The MacBook Air is super fun to handle. Consider the gains and losses though in going with it. If you move from the base 13" MacBook Pro to the Air, what do you gain? It is a little thinner and 1 pound less. What do you lose? $300, a much slower processor, less memory upgradeability, 40 Gigs of hard drive, battery life, one of the two USB ports, the only FireWire port, and Ethernet port, an SD card slot, and a built-in CD/DVD drive. That is a LOT of computer to lose for the sake of a little thinner and a pound less.
Any one of those losses could be a deal breaker for you. None of them would be for me. I don't use my FireWire often, I could get a USB hub for my desk, I could carry a little SD card reader in my bag, I could stop plugging my MacBook into the net and just use the wireless, and I never use my CD/DVD drive when I'm not at my desk. But, it's just too much computer to give up in my estimation. If you've handled the 13" alum unibody of the MacBook Pro, it still feels slim and lean and mean and quite durable and fun. But, if you don't need/use any of those things, $300 is definitely worth it for the smaller profile machine.
"How fast does the hardware go obsolete?"
Not very. Apple just completed a transition from the system software moving completely to the new Intel machines, so, that change won't come again anytime soon. The Unibodies represent the greatest physical durability to date, so the wear and tear on the case is vastly improved. I think you're foolish if you plan on using a new MacBook less than three years; I think you're naive if you think you'll want to use a new computer for 7 years.
"How is compatibility these days in general?"
It is fantastic. Essentially, for individual files and file types (word documents, graphics, web protocols, etc.), compatibility is essentially complete. For instance, your word documents between PC and Mac are just as compatible as they are between two versions of Word on the same platform.
You will still find some computer software categories where options are more limited on a Mac (though 99% of those are games). And, there are some web sites that use poor standards that choke on my Mac, though that has become VERY rare, and most often moving from the default Safari web browser to Firefox fixes the problem.
"Are there compatibility issues with AV support for doing presentations?"
Nope. You will need to carry in your bag the Mini DisplayPort to DVI adapter or a Mini DisplayPort to VGA or to Composite/S-Video (or all three).
"Are there software/peripherals you consider must-haves?"
I really like a MacBook sleeve that I then carry in a larger backpack of my choosing when needed. I love this Brenthaven Trek sleeve, since it is suitable as a carrying case or can be used inside a large backpack. One of the two I've bought for two different MacBooks is 4 years old, gets hauled everyday and is still in great shape.
Accordance Bible software is one of the best Mac apps I know of. It runs so natively and intuitively it is a joy to use and can offer just the resources and tools a scholar or pastor would want to have at their fingertips.
If you will be taking the computer between home and your office everyday, pony up and buy a second power cord and power brick to keep you from having to fuss with it everyday. You can then just unplug, slip it in the case and go.
Always carry an SD card and a USB flash drive in your bag.
"How is Word on the Mac?"
If you are familiar with Microsoft Word on the PC, you're still going to be familiar with it on the Mac. Most things are very similar. The approach to document creation is pretty much identical. Microsoft Word was originally written for the Mac platform. There was Mac Word before there was ever PC Word, and Microsoft Word is still the most feature complete word processor on the Mac. It has some junk I wish it didn't that I'll never use. (I'm looking at you, equations editor).
The only caveat, and it could be big for you, is that the Mac version does not allow editing of right-to-left unicode languages, including Hebrew. The next version of Word set to release at the end of this year may change that.
I would highly recommend that before buying Microsoft Office, you first install OpenOffice and live with it for a bit and see if this open source free software doesn't fit the bill. I would also almost recommend holding out for the next version of Word. If I was confident it would ship this year, I would for sure recommend that. There are other great and inexpensive word processor alternatives that are wonderful on the Mac, including Pages and Mellel.
"What are the concerns for viruses/malware on Macs?"
None. I've never had "virus protection" software on my Mac and I've never seen a Mac that had it. Ok, slight exaggeration there, but basically, short of you downloading illegal games and applications from torrent sites online, it's a non-issue still this year.
"Thoughts about music/video/games?"
There are plenty of games to run on the Mac, if that is an interest. There are not as many as on PC. The couple PC games I've wanted to play, I simply rebooted my Mac into Windows XP and ran it natively.
Music and video editing is pure joy on the Mac. The iMovie video editing software that it comes with is phenomenal. And as for music, there's some nice integration between my Mac and my iPod and my iPhone. :)
"Any other advice you have for a longtime PC user?"
If you do buy a Mac, I'd suggest keeping active on one blog or web site or newsfeed so you can learn a little as you go. A great option would be http://macosxhints.com