candle_86 wrote:Past that point games are largely DX9 and honestly a GTX 590 would support them just as well as a 6800GT
^This. When it comes to winXP newer is always better. I think you can go as high at GTX 7xx and Radeon 7xxx when it comes to XP. I've been finding HD 7870 and 7950 cards at really good prices recently - 35-40e for the 7870 2gb and 40-50 for the much faster 7950 3GB. The GTX 760 on the other hand held up it's price, costing about as much as a second hand R9 280X witch is a much faster card, so I can't recommend the nvidia 7xx series right now.
I'd have to say the sweet spot would be a GTX 580 or a HD 6970 if you can find one cheap enough - if not look for a cheap HD 7870 2GB - you can't go wrong with those.
I know these are modern cards, but some XP games are demanding (Crysis, S.T.A.L.K.E.R., etc) and since this hardware is cheap now, it would be a shame not to enjoy these games with everything cranked up to ultra.
Like I said, gf4 to 6800 are best used in 98 machines, and 7900/x1900/8800/HD2900 cards are just awkward valley. They do OK if you're not to picky about visuals in later games. A 8800GTX will net you 30 to 60FPS in stalker at 1600x1200 on high w/o AA and a little less at 1920x1080 - playable, but there are the occasional frameskips witch you don't get on a 280x for example. Two 8800GTS cards also work, but there's quite a bit of tearing and stuttering. Crysis really wants a GTX 480 / HD 5870 to run fluently maxed out.
If you limit yourself to Doom 3, Quake 4, GTA 3 and alike, a X1900XT or 7900 GTX will do very well - but at one point you will want to go higher.
Right now my collection of XP and later era cards include: 2x7950GT 512MB (XFX), 2x8800GTS 640MB (leadtek), 1x8800GTX (EVGA), 2xGTX280 (BFG and EVGA), 2xGTX 480 (gainward) as well as x1950XT (GeCube), HD 2900XT (OEM), HD 3850 (palit), HD 3870 (Sapphire) and finally a HD 7950 (sapphire).
When I built my first XP rig for eary DX9 games, I satarted with a single X1950XT. Then moved onto two 7950GT cards, then a single 8800GTS. I wanted to play stalker on my 27" widescreen LCD so I added a second 8800GTS, It ran OK, but I wanted to play Crysis on it since I can't get any audio from the game (steam version) on my main PC so I replaced them with a 280x witch can't really keep up with the game at 1920x1080 to my liking. Now I have to upgrade the PSU, get a Zalman GTX 480 cooler and use one of those OR use my HD 7950 and be done with it - witch is probably what I'll end up doing.