I recommend Mint because it’s basically Ubuntu with some extra polish on it and it comes with everything working. With most Linux distros, you have to install the non-free stuff like Flash and codecs and stuff. With Mint, it’s all working from the second you’re finished installing. You can fire up Firefox and watch a youtube video first thing. You also can use the Ubuntu forums for any issues you might have, since it’s basically Ubuntu.
We bought an Acer netbook at Walmart that has Windows XP loaded. It is OK, but we also own an iMac, and I hate the sluggishness and bloated feel that is Microsoft software. I get sick of the constant worry about viruses, plus the inevitable slowdowns as the registry corrupts. No operating system is perfect, but Mac OSX and Linux are far superior in terms of day-to-day usage reliability. It just works when and how it is supposed to work.