RAM speed. Important?

I have an Aluminum PowerBook G4 15" 1.67 ghz. The RAM currently installed is:

SO DIMM, 200 PIN, PC2-4200, DDR2-533

My question is, I went on newegg.com to buy some more memory and all 200 PIN cards don't match my speed and the ones that match my speed aren't 200PIN. I know the 200 PIN is obviously important, but does the speed need to be PC2-4200 or can it be different?


Thanks in advance

The speed and type of memory module is important. Instead of buying from NewEgg, go to RAM Memory Upgrade: Dell, Mac, Apple, HP, Compaq. USB drives, flash cards, SSD at Crucial.com and use their memory finder. They're the memory experts so you can be sure that you will receive the correct modules for your machine.

Regards.

It's listing compatable memory upgrades for my model and the speeds are all PC2700. Not sure where the discrepency is. Also, this website is a little pricey, which is why I prefer newegg, but it doesn't matter I guess because newegg doesn't have what I need.

It also says this:


Q: What memory goes into my computer, and will a faster speed be backward-compatible?

A: DDR memory with support for DDR PC2700 speeds.

Because DDR memory is backward-compatible, you can safely upgrade your system with any of the guaranteed-compatible DDR speeds listed below, even if your manual calls for PC1600 or PC2100 speeds.

I'm not sure if any of this is relevant because my speed is PC-4200.