Your issue extends futher than just SP2. With every Antivirus update, "what if" happens over and over. As such, the real question is "do you have what you can not lose on your backup?"
In closing, be sure you don't have any spyware on that machine and in all my experiences (100 first hand), nothing happens. For me it's been a boring service pack.
Best of luck,
ok, I am going to installl sp2. But have no way to back up.If something goes wrong can I use a restore point??????