Need advice on cpu upgrade

[shastamike]

Without adding a new motherboard, what is the fastest cpu I could upgrade to. Hard to find charts for this. Thank you.
Intel D915GAG motherboard
800mhz front bus
Socket 775
Current cpu is Pen 4, 3GHZ.
XP home.

 

[Reynod]

http://support.intel.com/support/motherboards/desktop/d915gag/sb/CS-026959.htm