1. Is it advisable for me to hire someone to install LInux rather than install it myself?
Only if you don't mind paying for something you can do yourself
2. Once it is installed is it user-friendly so that I can use the computer with a minimum of hassles? Or will the person that installs the program need to give me a quick run down? All I use the computer for is to surf the internet.
Get Mandrake/Redhat/Fedora/SuSE - easy set up, easy to use
3. Should the current Millenium operating system be deleted from the computer?
Definitely. ME was a horrible OS, even Microsoft admitted that. Get all the data off it that you want to keep and lose it.
4. Can AOL Instant Messanger be used with Linux?
Linux distros have many IM clients that can be used - Gaim, Jabber, Kopete, etc
Pick yourself a distro, install it (it's as easy as Windows nowadays) and stick with it. It's a lot more rewarding than Windows.
Welcome to LQ