What has sp2 done to my systems?

As soon as i dled and installed sp2 onto my laptop and my fam comp it has lagged the crap out of them right from the boot up; I tryed playing games(tryed various diff games) and fps falls to 1-9 (where it was always 50-60)... The systems affected are:

1.3ghz Pent M 512mb ddr wxp-p ati 9000m and amd 2600+ 512mb ddr wxp-h and nvidia 5200fx... The thing is it seems that both my sys w/512mb are affected and not my systems with 1gb ddram and similar setups... Its seriously pissin me off. Its Lagging everything I do; any solutions or anyone w/similar issues?