Intel extreme integrated graphics cards are not going to do you any justice on *nix. They work pretty good on windows with gaming but not on anything else.
You might want to consider a few things. Disable cupsd server while you attempt to play. Cups uses a lot of memory and cpu depending on your setup. Try a lighter window manager if your going to be gaming. Gnome is not really bloated at all that much but there are suitable alternatives if you do want to save at least a little cpu. Like fluxbox, or icewm. Close any unneeded apps while you play, like nautilus etc. I had an intel 845g once but the only thing I could play was tuxracer in fullscreen. But your model is a bit better so with a bit of effort you may be able to play minus the lag.
Another option is to start Quake and only quake in an xwindow session. You would have to adjust your .xinitrc file accordingly to that and I'm sure there is info on this forum of how to just play a game in a session and run nothing else.
And the last thing........get more ram. Never hurts to have more ram.
