The best program I have ever purchased for this issue, bar none, is Webroot's Spy Sweeper. Visit
www.webroot.com This program protects your homepage from hijacks, prevents inadvertent additions to your favorites menu, (this drove me nuts!), prevents installation of Browser Helper Objects, and has many other shields for stellar PC protection. This company is also the industry leader in spyware/adware/hijack research. It is very user friendly and has a free trial. There is also a free spy audit at the site. It takes only a minute or two, and it will tell you exactly what's hiding in your computer. If you do decide to purchase, the customer support is outstanding, and the price is quite reasonable for all it does.
As for SP2,
I uninstalled it about 5 minutes after I downloaded it. Microsoft seems to put out these patches/updates way too soon. It's still full of bugs. It does absolutely nothing. I tried to find one redeeming quality in it to no avail. Dump it!