First, buy your monitor. We won't go into detail about this here because the issues aren't at all specific to Linux -- you can find good guidance in any DOS-related buyer's guide. There's not a whole lot of price variance among functionally equivalent monitors (it's a mature commodity technology) so the basic question is "how many square inches of screen can you afford?".

This is one of the areas where pinching pennies is not a good idea. You're going to be looking at your monitor for hours on end. You are going to be using the screen real estate constantly. Buy the best quality, largest screen you possibly can -- it will be worth it. I personally shelled out $2000 for a 21-inch monitor in January 1996. Though I have no regular income and this represented a significant fraction of my bank account, I have never regretted it since.

The reasons not to pinch pennies are also reasons that you should should actually see the monitor you're contemplating before you buy it. A factory flaw like serious edge misconvergence or a tilted yoke is not a happy thing to discover just after you've cut a check.

You may want to consider looking for a repaired or reconditioned monitor with a warranty. These are often as good as new, and much cheaper.

Next, buy your card. The major issue here is matching the card to the capacity of your monitor -- you don't want to pay for more card than your screen can use, and you don't want to buy too cheap a card and find it can't drive your monitor at its maximum capability.

So once you've specified your monitor, find a video card with a maximum video bandwidth equal to or just slightly higher than the monitor's. That's how you know your video system is properly balanced, with a minimum of wasted capacity.

There is a fair amount of price variance among equivalent video cards, so shop aggressively here. If you're on a budget, one easy thing to trade away is bit depth. Manufacturers like to include 16- and 24-bit "photographic" color as sizzle in their advertisements, but unless you're doing something like specialty photocomposition work or medical graphics you'll never use more than 256. So you can settle for 8-bit color.

The days when XFree86 seriously constrained your choice of video card are long past. Just about anything you can buy in a clone system should work fine these days. If you're in doubt about whether the card is supported, surf over to http://www.xfree86.org and check out their compatibility list.