if you absolutely love nVidia, or simply want the fastest card that you can buy right now, of course the 8800 is the only choice. if you can't spend as much money, you have to cut corners one way or another, there's no way around it. if you want to see specifics, you can easily google for them--anandtech has plenty of reviews.
ATi just announced preliminary benchmarks for the new radeon 2900XT, and it beats the 8800 by a healthy margin. if you're an nVidia fanboy, there isn't much i can say to change your mind, but you have to keep in mind that this the whole point of competition: one company builds a better product than another, and they leapfrog to keep technology moving forward, and to keep the prices falling. if you only want one company's products, then you cut your options in half--so you just have to recognize that you have fewer options if you have a limited budget.
comparing nVidia and ATi stability in Vista is like comparing grains of sand on a beach. nothing is stable on Vista, at least not anywhere near as compared to XP. if you really want to run Vista (which you don't have to do until you start playing DX10 games), then you'll have to suck it up and deal with buggy drivers for a while.
the best thing you can do is simply to read benchmarks for performance numbers, and search your favorite retailers for the latest prices. anything that offers an opinion as to why ATi or nVidia is no better than stale bread--one week nVidia will be better, the other week ATi.
preliminary 2900XT benchmark:
http://www.dailytech.com/ATI%20Radeon%20HD%202900%20XT%20Performance%20Benchmarks/article7043.htmfor midrange, preliminary 8600 benchmark:
http://www.anandtech.com/video/showdoc.aspx?i=2975and the anandtech article that overclocked the E4300:
http://www.anandtech.com/cpuchipsets/intel/showdoc.aspx?i=2903looking at newegg reveals these prices:
intel E4300: $125
Gigabyte GA-965P-DS3: $110
Corsair XMS2 DDR2-800 4-4-4-12: 2x1GB for $130, or 2x512MB for $90