Less performance after upgrading

[OneZ]

Hi,

My old PC was { AMD X2 3800+ 2MB Cache, MSI K8N, 2GB DDR1, 7600GT, Windows XP SP2 32 Bit } and was able to run 2 copies of specific application with very good performance, after upgrading to { AMD Quad Core 940 8MB Cache, Asus M4A78 Pro, 4GB DDR2, 7600 GT ( same Video Card ), Windows 7 64 Bit } if i run 2 copies of that application the performance will drop.
Is that a hardware problem or OS problem ?
BTW, the application is World of WarCraft

Thanx.....

 

[superty12]

W7

There's probably not a version for Windows 7. So, yeah it still works with 2 instances open, but perfomance will go down.