Ventilo 2.1.4 & Mouse lag

My computer:
CPU: Intel Core 2 Duo E6750
Motherboard: P5KR
VGA: 8800GT 512MB

1) When I play some game, somethimes I don't hear my friends talking at ventrilo and after lag I hear everything what they said during a minute...
I tryed to change priority of ventrilo to belownormal,high or realtime but later win7 changes it back. Is some fix for it<

2) I have Logitech G15 and Roccat Kone. And I still feel little lag during playing games. I know it's not much, but gamers who play games like counter-strike 1.6 for a long time, know what I am talking about. I think it's in every game. So I can't be so precise at aiming. Can somebody fix that? (And yes, I have updated ALL drivers to the newest and Roccat released new drivers and firmware for windows7)

PS:Sorry for my bad English. :)
Thnx for every advice.

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