Confused with DDR2 RAM upgrade for laptop

I am looking to upgrade my HP DV6500t laptop from 2x1GB RAM to 2x2GB for a 4GB total. The original RAM is DDR2-667 (PC-5300). Would my laptop be able to take advantage of PC-6400 or PC-8500 RAM, or will it simply revert back to the PC-5300 performance?

Also, is all DDR2-667 RAM essentially created equal in regards to performance, or are there other details I should be concerning myself with?

Processor being used is Core 2 Duo T7300 @ 2.0GHz on Vista 32bit...if that makes a difference.

Crucial lists both 6400 and 5300 so it could probably run at the higher speed but HP cheaped out and installed the slower memory. Keep in mind that with a 32 bit operating system, you'll only get to use about 3.3 GB of RAM. Don't expect a dramatic improvement in performance since Vista is slow to begin with, especially on laptops, and that machine's getting old.

mike_d wrote in post #14465556
Crucial lists both 6400 and 5300 so it could probably run at the higher speed but HP cheaped out and installed the slower memory. Keep in mind that with a 32 bit operating system, you'll only get to use about 3.3 GB of RAM. Don't expect a dramatic improvement in performance since Vista is slow to begin with, especially on laptops, and that machine's getting old.

Getting old? I've been fabricating excuses not to replace it for at least 2 yrs now...one of which has been that I dread going through the selection/buying process again.