SP1 and SP2 are not competitive update, they are complementary update. SP2 fix the OS beyond what SP1 was fixing it. SP1 include security fixes and OS fixes that has been released from the beginning of XP up to when SP1 was released. XP2 include all of these fixes plus many more up to when SP2 has been released. Running SP1 now means that your computer may have some vulnerability that are not patched and is vulnerable to some hackers.
-Always put the blame on you first, then on the hardware !!!