There is quite a bit to SP2 that is great, with a few problems that didn't get any attention. Internet Explorer is a bit faster now. The MS pop-up blocker is quite effective and allows you to easily disable it for select sites. I run nortons as well, and all I had to do was go under the MS security thing that pops up and tell it that I use my own seperate software, and it stopped annoying me. I don't have any problems with it popping up telling me to update or any of that nonsense now. I don't remember exactly how I went through all that, but if you look around I'm sure you can find a posting somewhere on the net that detailed how to setup SP2 so that it was more acceptable of other software as well as less automated.
Another thing I liked was the addition of a web browser Add-Ons management utility. You can find that under the Tools menu in IE. It allows you to check all the browser add-ons and what they are related to, as sometimes sites can sneak them onto your computer. Makes it easy to uninstall crap you don't need. The basic Add/Remove program listing tends to manage faster as well. Those are just some of the things I have noticed myself, there is more that I have heard of but don't recall off hand.