VIDEONTTT6
Best to buy the 89w version, the 125w versions run too hot.
First check to see if you have the latest BIOS version, prior to upgrading.
More e521 processor upgrade info, can be found here:
http://en.community.dell.com/support-forums/desktop/f/3514/p/19268699/19466496.aspx#19466496
Bev.