Thanks for listing your system specs, that helps. Have you looked through my Tips on Troubleshooting Game Issues
? It "might" give you some ideals you might not of thougt of.
I'm still not exactly sure what your problem is other than "seems like no games run as smooth". Your system specs look fine, I just upgraded to an i7 system myself so I don't see the system being the problem. Have a look at mine.
Also, have you updated your DirectX Files? Again, look at my tips guide.
Let me know.