As to be expected of all upgrades of Microsoft OS's, there will be a few bugs. You shouldn't have to reinstall your programs ideally but since so many parts of your operating system will be changing, certain programs might experience a few glitches.
Whenever I install an OS, I always do a clean install because that way if you ever run into issues, you can isolate a problem right off the bat, and it leaves for a much better experience because you are not limited by how well it perforrms the upgrade (i.e. are you sure it caught EVERYTHING? )
So what I recommend doing, unless you have NO other options, is to burn all your important stuff (mp3s, school documents) to CD-R and just do a clean install while reloading all your programs. But you should be able to upgrade without any significant problems. I always say better safe than sorry though.
silver