O.K. thats my system:

CPU: Intel Core 2 Quad Q6600 @ 2.4 GHz
RAM: 4x 2GB Mushkin @ 800 MHz
Board: MSI P35 Neo
GPU: Nvidia Geforce 9800GTX 512MB
HDD: 1x Samsung 500GB via SATA 300
Power: 650W

Playing 5 WoWs on Vista x64 (1 with high settings 1650x1080 - 4 with low settings on the second screen) I'll getting 50-60 fps each client

AND my problem is fixed - Now I'm happy