Hi there
Any memory that is DDR 2700, unbuffered, NON-ECC will do according to the link you gave us to the crucial website. I recommend corsair memory, but there a bit more expensive, Crucial are slightly cheaper, just as good performance.
Crucial Memory
Ebuyer is a good site, i buy all my stuff from there (Y)
I see you have 512MB of RAM according to the crucial website. Do you really need any more memory? i would think that 512 would do, maybe a bit more if your doing some video editing.