Newegg.com GPU - http://www.newegg.com/app/viewProductDesc.asp?description=14-121-522&depa=0 Mobo - http://www.newegg.com/app/ViewProductDesc.asp?description=13-131-481&depa=0 Hope this helps.
Id highly reccomend getting something other than the FX-51 to be honest. The 3500+ will easily outperform it with a little overclocking, thanks to dual channel memory and a 1 GHz Hypertransport bus. However, with the super expensive ECC memory of yours, Id reccomend just replacing your motherboard and keep most of what you got-or make an Opteron server. There are a lot more ways to tackle this issue than what youve given us .
I honestly dont want to buy another processor.... this one runs great in most anything.... gets good scores of 11,000 cpu in aquamark and such.... plus i plan on OC'ing it a nice bit too with my new vapochill system that I bought... should get some good performance from it... minimum of 2.6 GHz (55 speeds) without any problem I suppose...