OS Change?

Hay guys,
I'm looking to change from Windows XP over to a different OS, and I was wondering what OS's you guys would recomend. A couple of requirements would be:
-As stable as possible.
-Able to be somewhat easy to use until I figure my way around.
-Able to be customizable once I -do- figure my way around.
-Able to run Windows OS games and software easily.
-NOT A MAC.

Thoughts?

>>1
Windows XP or Windows Server 2003, then move on to ReactOS when it's more mature.

>>10
if it is setup properly it is the most stable 9x OS
Yes it is, but 9x OSes all suck and went that way [points backwards in time]