Opinions X2 or FX60 Dual Core performing as a server

I am maybe trying to maybe cut some corners if possible. We are purchasing two new servers in the next couple of months. One of which will be Xeon due to contract obligation (bla bla bla). The other I am trying to find opinions.

The server I have full purchasing over will be a dedicated Web Server for our company, and also house a database engine with approx. 15k records. The server will also have the future possibility of offering anywhere to 3000-6000 email accounts.

I am concerned in how the dual cores will perform against an opteron server. I'm understand that the information is important which already leans me to server stability and swapable drives. But as far a performance how would the X2 or FX dual perform against two opteron processors. (No overclocking)

Well, server stuff isn't my area of expertise, but you might want ECC memory. You'd need an Opteron for this. Also, I'd definately go for a RAID with redundancy, RAID5 or perhaps RAID10 for a bit more performance?
I'd try an get an opinion from someone who is a bit more server savvy.

-mcg