Marianna's suggestion of ordering the disc is a good one, that is by far the easiest way, plus IF you have a problem, you have the disc. As Marinanna said, the programs that you have should be OK but there are still many that have conflicts. I'm going to post what I have been posting in the XP forum for months with a Microsoft link on it that also has a bunch of links on that page, please spend some time and read all of them, including the part about visiting your computer manufacturer's website to see if there are any program conflicts with programs that came on your computer. I have a new Compaq and I had to put 2 or 3 patches on BEFORE I installed SP2 back in September including one for system restore. Here is my post from XP. I realize that the first part of it you are OK on.
You have to be completely prepared for SP2 which means. Spyware free, Adware free, virus free BEFORE you install SP2, Also go to this link from Microsoft which also has links inside of it that will tell you what to do to prepare, including programs that are known to have problems which you may have to patch BEFORE you install SP2. Also go to your computer manufacturer's web site to see if any programs that came with your computer (non Microsoft programs) that need some sort of a patch BEFORE you install SP2. After all of the above, you should have no problems. Here is the Microsoft link. Hope this helps.