Does anybody know how fast the memory can go in these? The missus' laptop currently has not a lot of PC2100 (266?) RAM in it and I need to upgrade it as it's ridiculously slow. Trouble is, I can only get 512mb DIMMs for it on PC2100 flavour - Looking to stick 2gb in it eventually, but need 2x1gb DIMMs as the useless thing only has 2 RAM slots....