Wubi is fairly awesome. It will install Ubuntu (or Mint and other versions) just like a program inside WIndows. If you can istall software you can install Linux with Wubi. I will create a dual boot system so when you restart you can choose between Windows and Linux. If you decide you don't like it just boot into Windows and uninstall it like any other program. it's a great way to get your feet wet with Linux. If you installed one of the lightweight versions it could speed up your computer. If you install the full versions ie regular ole Ubnutu it probably won't speed it up.
I still haven't tried this one... but I have every intention of doing so.
It really is not hard. I would start with Mint (based on Ubuntu). Download the iso and burn it to cd. Pop it back in and restart your computer. It will run as a live disc and let you check it out before installing. Wubi is built in but to install with Wubi boot back into windows after removing the disc. Once windows is up pop the disc back in. It will open a window and ask if you want to install inside windows.
http://www.linuxmint.com/download.php
If you need software to burn an iso I would get Burnaware free.
I've used Speed fan in the past. Mainly only used if for overclocking purposes. It can tell you a lot of techy information about what your core processor is running at and all your system temps. Pretty much just a good way to check your system vitals so to speak. It's a great program but yes it is a little more for the advanced user.
I hope that after I die, people will say of me: "That guy sure owed me a lot of money.''
Yes! Thanks so much CK! I can't wait to try some of this out on my old-as-dirt computers.