Most of the major Linux distros have good support forums which will help you with any problems you encounter. The one general bit of advice I would give is that you must try to be open-minded. Lots of people who've been using Windows for years try out a Linux distro and quickly get frustrated because it doesn't work the way they're familiar with, i.e. like Windows. You might have a look at
http://linux.oneandoneis2.org/LNW.htm for a fairly comprehensive look at that issue.
You've started off with Ubuntu, which is a popular choice. You may or may not like the GUI which it uses (Gnome) which is very different from Windows. Kubuntu is a spinoff from Ubuntu and uses the KDE desktop, which is much more like Windows in style. I see that Mepis is on your list, and that uses KDE too, and is pretty user-friendly. Most friendly of the lot (IMO) is OpenSuse 10.2, which was recently released.
Installing hardware isn't the nightmare which it was a few years ago. Most printers, scanners, graphics cards, etc work straight out of the box, but avoid Windows-specific hardware like GDI printers and Winmodems.
The bottom line is that you need to spend some time learning things, because Linux is very different from Windows. If you're prepared to give it that time I think you'll find it a rewarding experience. Good luck!
Eric