Credit: from BrashEndeavors on the Everquest2 forums.
GeForce cards are fine as long as you buy the right GeForce cards. That's the same with Radeon.
I have both NVidia & ATI cards and they have done very well by me. But if you buy an entry level card meant to allow families to watch DVDs at home or business computers to run Powerpoint -- such as a GeForce 6200 or a Radeon 9250 -- then yes you are going to be very disappointed in your purchase.
A very good tipoff when you have no other information to go by -- the last three digits of the card usually signify their intended audience:
- Cards that end in 100-300 are entry level cards intended for business applications & general multimedia (nongaming). Usually they will do poor in games (there are a few at the upper edges that squeak by ok in games, such as ATI's x1300pro).
- Cards that end in 600-700 are usually midrange cards geared more towards gamers. Choices such as the Radeon x1650pro or GeForce 7600GT usually give excellent performance in games for their price
- Cards that end in 800-900 are higher priced "enthusiast" cards aimed at gamers who are willing to spend more for the best performance. This is why the older Radeon 9800pro and X800XT cards are still often a very good choice over newer "budget" cards that end in 100-300. You can often get a great deal on secondhand versions at ebay.
The first digit on the card usually signifies a series or family of cards. So a GeForce 7300 is a low end entry card from the newer GeForce 7 series, and is NOT as good as a 6800GT from the GeForce 6 series, despite its' apparent "higher" number. Likewise, a newer radeon x1300 from the ATI X1 series is not as good as the older X800 cards, despite having a "higher" number.
You can usually also gain some information from any prefixes or suffixes. The entire FX series line has trouble in any pixel heavy games, such as Everquest2, NWN2 or Oblivion, although they might be fine for older or less demanding games such as Sims 2 or World of Warcraft. Cards that end in "LE" usually have so many crippled features that they are often worse than cards several levels lower. What makes it more confusing is that "GT" suffix on GeForce cards is good and signifies a higher class of card, but on Radeon cards is bad and indicates disabled features. Reverse is true for XT suffix - on Radeons this is very good and signifies the flagship cards, on GeForce it is poor. I don't know if they were intentionally trying to be deceptive in re-using the other company's "preferred" suffix. The 6800XT is an example of a card that "sounds" good but performs worse than other cards a level lower.
It can all be very confusing. When in doubt, it's usually best to check on forums with gamers who actually play the same games as you, as they usually know which cards have issues or exceptionally good value.
People who can only use PCI cards are in a bit of a fix because they don't have the wide selection and choices that PCI-Express or AGP has, and they have to pay much more for the older technology. Usually this happens with entry level Dell/HP/Compaq systems aimed at a budget market. Sadly these computers usually have motherboards originally designed to handle PCI Express, but the manufacturers literally removed the PCI-E slot from the board design to save $5 in production costs, and there is no way to ever get it back again. These budget systems will also have very weak power supplies, usually 250W or less, that will have issues with more powerful cards.
Anyone who is looking to buy a PCI-Express card, should probably hold off till March if they can. Both ATI & NVidia will have a new slate of DX10 cards, some very attractively priced high performance cards (such as the 8600GT for $149, and a new $299 320MB version of the 8800GS), and this is going to cause a ripple down price cut in older DX9 models as well.
AGP owners won't benefit as much as they are competing among themselves more and more for a rapidly shrinking pool of "good" cards. It's unlikely there will ever be an AGP DX10 card, but maybe we'll be surprised ^_^ as I don't think most people expected there would ever be an AGP version of the Radeon x1950pro or GeForce 7800GS (which are currently the best AGP cards on the market).