Not really. I have found most of the lag issues in multiplayer games are directly related to the connection type and quality of that connection more than local hardware issues with the possible exception of the vid card. You'll get more out of going to a 333/400 FSB platform board than you will with JUST a processor increase.
I presume of couurse you are playing multi type games, maybe not. Bottom line is: not as much as you think. Other things are more important.
Gigabyte GA-7VAXP F13 bios
Barton 2500+ @ 2366 @1.75 Vcore actual speed (SANDRA PR RATING 3700) 9500 Pro @ 340/310 Mhz. Antec 1080 plus w/window and blue LED fans 450 watt suck-ply Will swap for A64/opteron when prices get reasonable.
Rig # 2 - Mac G5 in about 3 months after the dust settles. *Quit* Apple bashing, the G5 is a good product and a GIANT leap forward for that platform.