An easier option that doesn't involve touching the registry:
Download and run spybot search and destroy from
http://www.safer-networking.org/en/index.html. It's a freeware program thaat you really should have installed anway as it keeps your system free from spyware and adware.
Providing you have the "advanced" mode selected (mode menu), you are able to get a list of all processes that run on startup and enable/disable/delete them. Disable anything that you are pretty sure shouldn't be there, then reboot. If, after many days of switching on and off you find nothing you want to use has stopped working, you can safely delete those keys that you disabled. Don't delete anything outright immediately just in case!
HTH
PS I'd still take trache's advice of look and not touch, just so you can see what the registry looks like. It can be scary at first glance but is actually laid out fairly well.