Can I use Kingston RAM in a MacBook Pro?
I upgraded the memory in my Early 2011 MacBook Pro from 4 GB (2x2) to 8 Gb (2x4) using the Crucial site, and haven't had any problems at all.

For the record, I also did the same with a brand new iMac, swapping out both memory modules with 2x4 GB from Crucial. 

It worked out to be about 1/3 of the price that Apple charges for the same memory.