Longevity is important in the sense that adapting to a a new computer every X months is painful.
I agree! What I meant is that you can buy well in the low end of the market and still get a machine that will last 6, 7, 8... years. We've talked about it, I find the Mac you bought for your wife completely crazy. It's going to be *high end* for several *years* compared to the bread-and-butter computers, and probably seriously overpowered for anything the two of you can think of *together* until its EOL. Given Apple's pricing of the high end machines, you could have bought a MacBook for every room of your place for the value of that single Mac, I guess. (Depending on your place, obviously. *g*)
BTW, moving from one machine to the next has been absolutely pain-free with Apple at least since 10.4 (2005) when Apple bundled the Migration Assistant (which was available only for certified technicians before) with the OS. I've yet to see it fail, and I've migrated users with all their software and data over several machines and architectures. In fact it is so reliable that in one of my former jobs, we would often give the high-end users (3D artists, Photoshop people) the newest high-end machines migrating their old machine to the new one, then giving the machine to another user (again migrating), sometimes shifting around up to ten machines in one batch. Migration itself only involves connecting the machines with a FW cable, booting the old machine in target mode, and starting the Migration Assistant on the new machine. (It even restores Adobes legendary piles of shit without having to reactivate them, but that wasn't always working because Adobe's licensing itself doesn't work well (mostly it doesn't work at all unless you have your own license server in-house).)
If you happen to do Time Machine backups (and who doesn't?), you can even just reassign the old machine and "restore" the new one from the TM backup. Yes, of course that also works with backup servers in the network, even with Windows servers. No need for Time Capsules or OSX Server.
But I digress. It's hard to not get excited about the ease of administration Apple delivers with bundled tools. I might sound like a fanboy, and OSX Server's got lots of bullshit going on at times, but I can just say that I've never had any trouble with my OSX boxen at work I couldn't fix within a few minutes and with bundled tools. (Hardware failure obviously excluded.)
Upgrading is graphics cards will eventually be needed, but what is it going to cost? 200 in a few years.
Ah, I think we know different kinds of gamers. I know quite some hardcore and professional gamers, among them ESL pros, and their graphics cards are all in the 400+ camp, with multiple identical cards per system to further boost performance. This is both the amateurs and the pros. And those cards are usually exchanged after one year at *most*, and all at once to minimize problems. Mixing cards can be a compatibility nightmare, I've been told. And once you've seen Battlefield: Bad Company 2 or the new Medal Of Honor on a 30" screen at 2560x1600 with full details and compare that to my 1440x900 at medium detail (which already looks great!), you know that power is really needed. If you get the chance to look at the games in that resolution and detail, absolutely do so. It's incredibly real, to the point of being photorealistic. Oh and yes, it makes a LOT of a difference, too - you can spot and shoot people before they even notice you, just because of the higher resolution.
When buying OEM machines you usually get stuff you don't want (LCD, keyboard, mouse... Why?) and insure that more stuff needs to get thrown away.
I agree, however the smaller chains and shops usually offer rigs without all of that (and most importantly, without unneeded Windows licenses). I've gone and bought some of them for friends needing new hardware, and it has the advantage of getting a pre-built machine (usually with good components, too) without having to hunt down every individual part. Plus, you get warranty for the whole system, which is nice. In the store where I usually buy, you can bring the machine in, wait 30 minutes max while they fix it for free, and take it back home. You don't need an appointment for that, just bring in the machine. I never had to argue with them.
Windows 7 isn't so bad, BTW. I only have one friend running it (one of the gamers, but he's got no computing skills whatsoever, having started at 42 and being a truck driver), and he hasn't managed to break it yet, IIRC almost one year now. It's an ugly train wreck concerning the admin UI (of course everything has been moved around AGAIN), but it's pretty solid. The only problems he had came from insufficient cooling. (Yes, this can still be insufficient for a gaming rig. I couldn't believe it myself.)
I'm looking forward to updates on how your brothers fares with 7! I think he won't get many problems unless he installs everything he stumbles upon, which is not very probable given he's your brother.