Originally posted by: P0ldy
"UT2k4 is what I play right now. Doom3 has a port. Others do too."
And do you have a Windows boot to compare the performance between the two OSes? I'd be interested in hearing what the differences/advantages are.
Games mostly work better in Windows. A tiny bit faster, maybe, for native Linux games vs Windows games.
It all realy depends.
You have several different 'games types' on linux. You have Free games (free software, not no cost software), most of these are smaller and more old school. Some are nice and modern, but those are the exceptions and they lack the polish that commercial games do.
Stuff like bzflag, flightgear, gl-f117, torcs, scorched 3d, mame, worldcraft, frozen bubble, gl billards, etc etc. Literally hundreds, but some you have to compile yourself...
Then you have big name native linux games. Things like Postal 2 (hehe, I know it's stupid), Unreal Tournament 2003/2004, Doom1/2/3, Quake1/2/3 America's Army, Neverwinter Nights. These are the minority, and quality and finish are the same as Window's versions. Speed varies, but is within a few percentages. Nothing to get excited about.
Then you have independant games and smaller game makers which most often make multiple ports for their games. These are my favorite...
Lore, Vendetta, Bridge constructor set (it's fun, actually), marble blaster. Stuff like that. Cheap, not made by assholes, and fun.
Then you have the native windows games that work thru Wine and Cedega. (Cedega is a commercial version of Wine)
The free version of Wine has very beta DirectX 9 support and can run some newer games like Worlds of Warcraft, and Pirates!. But this is for only people who know what they are doing, at this point.
Cedega offers commercial support and often game makers work with Cedega to make sure that it works in Linux. They deal with CD copy protection and stuff like that. Otherwise you'd have a hard time installing most games without Windows.
Right now I have a copy of Cedega I installed thru 'Point2play' for my game Sid Meier's Pirates! (which I loved playing the original versions years ago)
You can play newer titles like World or Warcraft, Half Life 2 (and STEAM) Sims 2, and so on and so forth.
Not all games work, working games are rarely 100%. And Cedega costs 5 bucks per month, minimally 3 months. But you can keep on using it when it runs out, you just can't get any new updates.
Wine and Cedega, are NOT emulators, they are programming libraries that create a Win32 API enviroment inside Linux. There is a performance penalty, but only because it's not as nicely done as Windows own Win32 support. (and won't ever be).
For Applications in general you have option of using Wine or using something like Win4lin, which will run Windows 9x operating systems at near native speeds inside Linux, so that applications that won't work in Linux you can use without having to dual boot. Probably not that usefull for newer games, though.
For Gaming on Linux right now, there is plenty that you can do to occupy your time and have fun. But it's only worth it if you want to use Linux for other reasons (price, Freedom, politics, stability, security, etc)
There are some hardware considurations...
Best hardware setup is a Via or Intel motherboard. Nvidia video card, Audigy (not Audigy LS!) sound card (or possibly a envy24 or envy24ht-based card).
Don't bother with 'onboard' raid0/1 setups. Linux software raid is faster and more stable (those onboard raids are like the winmodems of raid hardware) and Raid 0/1 on a desktop is mostly a waste of money.
Stuff like that.
The linux game tome. Massive database of Linux games.
Tux games. Sells Linux-compatable games.
wine application database, database of apps and wine compatability.
icculus.org is the homepage of a big Linux gaming guy.
Linux Gamers dot net Linux gaming news, and some howtos.
Linuxgames dot com Linux gaming news and community stuff. Like above.
linux militia like above
GarageGames Maker and reseller of independant games. Many with Linux/OS X versions. Recently released Dark Horizons: Lore, which is a massive online multiplayer mixed in with first person shooter... haven't had time to try it out yet. (games are around 20 bucks and you can install them on multiple machines thru downloads.. keep honest though.

You want them to keep on making good games. )
Transgaming makers of Cedega (formally WineX). This is there game database. Only realy pay attention to games with 4 or 5 stars. 3 stars is borderline, depending on the game and bugs.
so on and so forth. You can find more information from google.com.
Linux for newbies can be very frustrating, but once you have it setup and are familar with it it becomes as easy as Windows. Takes a LOT of adjustment though.
See my sig for a link to good guides, they can be usefull for understanding what is happenning when you do stuff in Linux.