AMD Athlon 64 3800+ X2 runs at 2.0ghz.
You wont see much of a difference running 64bit because all apllications are still 32bit. You might see a slight increase in performance when loaded the O/S.
A+, Network + , HP Certified Tech and MCP
Specs: AMD Phenom II X6 1095T, Asus M477TD, 8GB GSkill Ripjaws DDR3 1600 7-8-7-24 1T, 128GB Crucial M4 SSD, ATi HD4650, W7, 27" HL272 Monitor