I'm in the same boat as Staticon as far as operating systems go.  But I do know that Mandriva is a fairly good operating system.  Just stay away from Solaris 10, which is Unix.  It's a powerful OS made by Sun Microsystems (you know, the guys that make Java) and you can get it for free now.  Threw that in my laptop after making sure it was compatible, took even longer to install than XP.  To top that off, you basically have to manually configure Solaris 10.  Recognizes only 1 mouse,  as well.  Also could never get my audio to work.

But never go with Vista.  2 very major problems with it right out of the box that I do know of.  IPV6 is the internet protocal of the the future.  Haven't gotten there yet, we are still using IPV4.  Vista comes with IPV6 activated.   DHCP networks.  It only likes Microsoft DHCP networks because it has something call a DHCP Broadcast Flag, now you can remove that flag or turn it off by going into the registry, but then again, if you go into the registry and you don't know exactly what you are doing, you will turn you pc into a very large paper weight.  There are also other problems, many more, but I don't know what they are.  YAY Microsoft!!!!!!!  They did all of these things because your average pc user doesn't know how to find network settings or edit the registry and many other things, so that way they have to pay Microsoft more money to get them fixed.

Your best bet is sticking with XP until they make it to where you can't use it anymore, get a mac, or find a linux system that does it for you(there is a multitude of them out there).