What are the specs of the RAM that you bought? Brand, speed (supports DDR2 533mhz, or PC2 4200). Got that from the Amazon product page, couldn't find anything else easily.
This looks like what you need, based on that Amazon page. One of two 2gb (2x 1gb) packages from Newegg (the other costs a couple of dollars more).
Also, according to the Amazon page, this only supports up to 2gb of memory, while the first link that sanddrag posted that said 4gb... so look on some forums/reviews to find out before you upgrade to 4gb (if you ever do).