FX60 or opteron, for a SQL server...

No overclocking is going to be done...

I'm looking to build a SQL server. We currently running SQL on a Dual Xeon 3.06 DELL all SCSI, 4 gig of RAM, 3 x 74gig in RAID 5

What would be a good replacement for this box in terms of CPU's and mobo. I'm a big fan of AMD, but never used them in a server environment. Since its all disk I/O, having the fastest CPU might not be the answer..

Any thoughts?

Since the FX is a gaming processor, I would go with an Opteron. The FX is overkill. Go with something like an Opteron 170/175/180. You could also look into a Dual Opteron, like the 270/275 models. The nice thing about the 1xx Series, is that you can get them in the S939 variety.

SQL relys on physical memory more than it does storage for performance, although both are important. How large is the storage area for this SQL server going to be? How many active queries will the server be responsible for every min?

I would suggest an Opteron as I'm pretty sure you won't be overclocking this server. The FX's unlocked multi would be wasted in this environment unless for some strange reason you wanted to overclock via multi only rather than ramping up both CPU & memory speeds.