It looks like you can take a maximum of 2 GB (1 GB in each slot) and, since they offer to sell you EITHER PC2700 or PC3200 it's safe to assume that PC3200 will work just as well (your system will clock it down to the right speed). This is sometimes beneficial to know, because often the faster speed is cheaper. I would then go to Newegg and search for the best deal on either of these speeds. At a minimum, I would replace the 256 MB stick with a 1 GB stick. Then it's up to you whether you want to max yourself out by replacing the 512 MB stick as well.