sp3 or sp2, it isn’t an indicate for being safe on the internet.
sp2 with sandboxie will probably do much better than sp3 without it.
and if you have 3 softwares in the defense line, without counting sandboxie, believe me, it will detect almost 100% of the viruses, and the rest will be blocked
by sp2 and sandboxie.

and for proves…
http://answers.yahoo.com/question/index?qid=20090529111720AAOv4Ww

  • sp3 is not compatible with all the softwares which run on sp2.
  • there isn’t such big difference between sp2 and sp3, just a bunch of windows updates… that’s it.