It's always good to plan for the future, but constantly craving top-of-the-line performance will ultimately drain your wallet to no end since new technologies are being introduced all the time. If you've got a near-unlimited budget and want the finer things on a regular basis, then there's definitely nothing wrong with that. There are quite a lot of people out there who want to crank the resolution and every possible effect up to the max so that the game they're playing looks the best it can. I happen to think that's unnecessary.
To me, looks are only worth so much. It's great to have every detail in its prime, yeah, but what matters to me is if the game in question will run under reasonable quality settings. I'm not picky and I don't focus on the video card getting every last detail as perfect as it can get. I've had a Gigabyte Radeon 9600 XT for many years now and I can tell you right now that it's managed to run everything I've thrown at it. Call of Duty, Starcraft, Warcraft 3, Guild Wars, Half-Life 2, Doom 3, and just about every other game I've ever played have run very well on it at 1024x768 resolution without any overclocking at all.
I chose a card that would perform well for years to come without worrying about the little things and I've probably saved myself a heck of a lot of money because of it. Who cares if the lines look a little jagged once in a while? I don't even notice things like that unless I concentrate on them, and when I'm playing a round of HL2 or CoD the last thing I'm worried about is if the scenery looks pretty. I still get great framerates with the games I play. The card is finally starting to outlive its usefulness, but that $150-ish investment I made all those years ago really paid off.
Just go for a card that'll have a good, long lifespan and don't worry about having everything look perfect. Get a high-performance, reasonable-priced processor like a Venice 3000+ to go with it and you'll be set for a while, I'd imagine.
