OK guys,
first up: sorry for the long time afk!!!!
I now changed OS to win7 and the problem is no longer existent.
My conclusion is that some drivers (maybe motherboard) must have caused the problem since befrore I went win7 I did a complete new installation of my win xp.
For all you still stuck with the problem - hopefully the new driver (260.xxx) will solve the problem.
Btw. check with latency checker if you get those spikes as well
Again, Thank all you guys a whole lot for your help !!!!!!!!!!!!!!!!!!!!!!!!!!
first up: sorry for the long time afk!!!!
I now changed OS to win7 and the problem is no longer existent.
My conclusion is that some drivers (maybe motherboard) must have caused the problem since befrore I went win7 I did a complete new installation of my win xp.
For all you still stuck with the problem - hopefully the new driver (260.xxx) will solve the problem.
Btw. check with latency checker if you get those spikes as well
Again, Thank all you guys a whole lot for your help !!!!!!!!!!!!!!!!!!!!!!!!!!