Well i though about this idea so i had go to see if it right i had 2 pcs all the same specs each other (i.e 2ghz etc) and both formatted and reinstalled Windows XP on both and updated one wiv SP1 and the other wiv SP1 and SP2 and came out after few tests that SP2 was slower that SP1 by 1 secound personally probly the reason is that the SP2 is more Information on the XP O.S were SP1 anit but personally 1secound wait anit that Nasty