STL - Watching this thread, do you have the answer you need now?
It's all very well saying that you can get Linux to do what you want with a little tinkering etc but it still comes down to - "What do you want it to do?" and "Do you have time to make it do it?"
Cheerio is right - if you want a simple desktop o/s, and all you need to do is surf & send email then Linux is a great way of getting more bang per buck out of older systems and I agree that Suse or Ubuntu make easy work of this.
However, try to go on a step and set up networking with other systems, printers etc and you start getting into the need for some skills. My personal bugbear with my Linux desktop is media - trying to get media players working to accept internet radio streams
My personal test on this is the "help test" - if I put Linux on a PC for a member of my family, how often would they be asking for help. The answer sadly is far more often than with Windows, and I get asked enough with Windows as it is.
As you say STL - a bit of experimentation is the best way to tell if Linux is what you want. Beware installing it on your windows PC as most Linux versions overwrite the boot loader with GRUB or LILO which works well but is a tough one to back out of if you ever want to clean Linux off the PC in future