SP2 is junk, it ran like sh** for me.
My Reasons=
1. Keeps on telling me that I do not have a Firewall (I do)
2. Keeps on telling me Virus Protection was not detected (I have A/V)
3. I disabled the Microsoft Security Center.
4. When I had 512mb of ram, i used to have approx 350mb of free phyiscal memory. But when I went to SP2, I only had 250mb. 100mb were eaten up by SP2.