My brother's laptop needs a RAM upgrade. Using Newegg's memory finder wizard returns only PC5300 DDR2 ram modules. PC6400 memory is actually slightly cheaper. Is there any problem with putting PC6400 memory in a PC5300 laptop? I assume that the memory will just run slower, at PC5300 speed. I've done this before on a desktop computer and it ran fine, but wondering if PC5300 would deliver better performance.