How much of at Bottlekneck?

[LRTom]

Hi

I'm running :

Asus A8n32-SLi
Opteron 144 @3.06Ghz
SLi'd 7800GT
2GB standard memory at 214 Mhz, 3-3-3-8 2T

How much of a bottlekneck is my memory in the system? It is a gaming rig.
If an upgrade was worth the money, what would match my system nicely?

Thanks

Tom