Not all teenagers screw up computers as you guys may think. Im 16, and my computer is as neat as it could possibly be. I keep all my folders organized, I run Ad-Aware and a anti virus, make sure i Google programs before I download them to make sure they dont have Spyware and run Kazaa Lite++ and eMule. For my messaging needs, I run Trillian since it combines all the IM programs, AIM, MSN, Yahoo, IRC, and ICQ into one program, and I like the fact that Trillian automatically logs everyo conversation automatically. Granted it may be because I have a boatload of computer knowledge, but I still hate to see unorganized, messy computers.
You guys might wanna try out "RegCleaner" one of these days, it cleans the registry of unused key/values and could speed up your computer if you have enough unecessary entries.