Looks like you currently have a Pentium B960, which means you have Socket G2; your motherboard/BIOS accept Ivy Bridge processors, which is not always a given for Sandy Bridge laptops. If you want to go quad-core, you can get something like the i7-3632QM, or if you'd rather have single-threaded performance the i7-3540M is your best bet. Basically any Core ix-2000 or ix-3000 chip will work as long as it doesn't exceed 35W; this means you have to avoid CPU's with model numbers ending in XM.