Hey guys, my board still good?

[KraidSaves]

I built my computer about a year and a half ago I believe. Its an MSI P6N SLI-FI. Since then I really haven't been keeping up with hardware advances and I'm wondering if its still good. I've ran into some money and was thinking of building a new rig but then thought maybe all I'd need to do is upgrade.

First of all my processor is probably the weakest I could get. Its a E2140 OC'd to 2.66ghz (original 1.66ghz). I mainly play WoW with it but I know that I have to be bottlenecking my rig with it even at overclocked status because I do get choppy in heavily populated area's of the game like big cities. I thought maybe I could upgrade my CPU, PSU, and Graphics Card and maybe even a second hard drive. My main concerns are the PCI-Express slot being able to handle the new video cards. I know they are some kind of PCI-E 2.0 or something and want to know if my mainboard will not be slowing its performance should it have an obsolete version of the PCI-E slot now.

Really I just want something that'll play my games better. WoW, COD4 ect. I'm understanding that the new Q9550 quad cores will not really improve gaming over a high clocked Core2duo. I don't want to break the bank if I don't have to I just know that the 1mb cache on my 2140 is probably killing me.

Upgrading from my current rig would be much easier and cheaper than buying a new one. Any help or thoughts would be appreciated.