From what I've read about TW Linux version vs Win version the linux one runs smoother without freezes and other stuff. Also lots of people had reported increase in frame rate.
Thus I think running games under linux is not bad stuff
Another significant issue is memory.I've get significant gain in AH perfomance when 256MB additional memeory were added (now it 512) to my Laptop I usually fly with it (1.3Ghz Radeon 9000 32Mb).
If you run 256MB computer then you get 180-200MB "eaten" by Win XP and graphical applications require lots of memory - you do not have really enough resources.
However when I run my Linux PC wiith Fedora Core 3 with Gnome I get only 80-100MB used!!!! Thus the rest remains for applications that is important for graphics.... it may significantly gain the perfomance. And if you really want to reduce amount of used memory (for low end compuers) you may not run Desktop when you play some kind of games but lightweight window manager.
Another - antivirusesI do not want to disable AV at Windows in order to run game smoother - but if AV starts some kind of tests it can dramatically reduce perfomance of the PC...... As we know anti virus is not issue under linux
Same about different spyware that takes lots of memory and requires antispyware soft to run
So let's see and wait how MS makes more and more bugs and security holes and is pushed from the market.