The X800GTO comes highly recommended for online gamers. It is simply the best bang for the buck card for games like BF2, Half-Life2, Counter Strike, Quake3/4, UT2003, etc.etc.
It has a full 12-pipelines with 256 bit memory interface. This allows you to not only play meatier games, but at higher resolutions and room for adding additional texture filtering (anisotropic filtering) and even AA in most cases without much measurable detriment in frame rate.
One thing to know though is the X800GTO is a PS/VS 2.0 card. This means the rare/few NEW games that support HDR will only allow bloom on this card. You can use HDR on Source Engine games though (such as Lost Coast or Counter Strike). It's just the rare few FP16 HDR games available. There aren't many of these games: Oblivion- which the X800GTO still plays incredibly well at high resolutions and all other settings maxed, and a few obscure titles (Splinter Cell, the latest Tomb Raider, Age Of Empires III will get *slightly* better looking water with SM3.0 vs 2.0, etc.).
It basically trades FP16 HDR and SM3.0 for blazing online game performance.
Unfortunately, you wont find a 12-pipe card with 256 bit memory interface with these features anywhere near this price point. Which is a bit silly also since FP16 HDR and SM3.0 also have a very large performance hit associated with them also.
For avid online gamers, I usually recommend/implement the X800GTO's as some of the Sapphire models will come with 16-pipes vs 12. And while I do not recommend it, many owners have also been able to unlock those 4 extra pipes by flashing the BIOS. Even at 12-pipes, these are several fold faster/more powerful than their closest price point match at the most popular games.
They DO consume a lot of power though and also can get pretty hot. They do assume a good power supply and adequate case ventilation (i.e. a fan or two). For BF2, they have zippo slow downs even in the newer Armored Fury and Special Forces maps, whereas our 6600GT (8-pipe job) has a number of slowdowns in these games.. plus lots of framerate dives when piloting a jet.