S1G4 procs can't be used in S1G2 sockets, primarily because they require DDR3 RAM. Your only real upgrade option is a Turion X2 RM-77, which is a whopping 100 MHz faster than your current proc. What's more, RM-77's go for $35+ on eBay, while RM-75's can be had for under $4.50. You're better off sticking to what you have.