Early '08 MBP Memory Advice

[matt07lx]

I've read that my MPB (early '08 2.4 GHz 15 inch, pre-unibody) can actually support up to 6 GB of RAM despite Apple's specs of 4 GB max. I currently have two 2 GB 667 MHz DD2 SDRAM (Kingston) in my machine. I was thinking of switching one of those out for a 4 GB chip. My question is, would it be wise to use a different brand chip for the 4 GB (say, Crucial?) or is mixing types a bad idea? Also, does speed make a difference? Would a 800 MHz chip cause me problems paired with a 667 MHz 2 GB chip?

I appreciate any advice you guys have. I've done my homework on RAM but the details still confuse me...

 

[alust2013]

Brand shouldn't really matter, but definitely get the same speed. Different speeds can cause issues.