Does the frequency/speed of RAM matter hugely?

As my tower's motherboard shorted, i'm stuck with a six year old HP Pavilion ZV5000 laptop. I have two (don't ask ), and i'm using the better of the two, with a 2.0GHz AMD Athlon 64 'Clawhammer', 40GB IDE HDD, 512MB RAM (2x256) and 64MB of video RAM. I would ultimately like to upgrade the RAM to the 2GB max., but that would cost £60, which I don't have to spare at the moment. A friend of mine recently upgraded the RAM in his laptop from 2x512MB to 2x1GB, and offered me the 2x512MB sticks. Obviously, my first concern was was it the right type. Off the top of my head, the ZV5000 takes SODIMM 333MHz RAM. I enquired, and my friend said the RAM he has is 600MHz (from what he could remember).
If they are the right physical size, would the difference matter/damage the laptop?

Assuming the RAM is compatible in all respects and differs only in the speed rating, it should work. The new RAM will likely operate at the same speed as your other RAM (333) rather than 600.

I've never heard of incorrect RAM damaging anything, but it might not be recognized if it is incompatible in some respect (other than speed). The primary considerations are form factor and voltage.

You'd have to actually try it to confirm.

I garrantee if it's the wrong ram the computer won't boot.

ok, thanks both for the advice
(ignatzatsonic, apparently i've repped you too recently, but will do so once "i've spread some more around")