Which upgrade from core 2 6400??

[Winy68 b]

I'd appreciate advice or opinions on what's a good upgrade from my core 2 6400 that's on my NVIDIA nForce 680i SLI LT Motherboard

I'd like to keep my mbrd memory etc and just plug in a faster CPU

I'd consider buying a new mbrd combo but I'm trying to keep cost to a minimum

I'm a little embarrassed to ask. I used to be pretty current on hardware but not so much anymore I don't do gaming etc mostly acts as home server file server web browse office work etc

I cannot recall my memory I have two stick. DDR I think

Anyone up to speed?

Thanks in advance

[pcpubay]

http://www.evga.com/support/motherboard/nForce_Intel_CPU_List.pdf