Reply to Which OS?

I'm believeing of a clean install of my operating system. I've just got the S4 and although it runs ok i really want it to be as stable as possible. My PC specs are:
dell inspiron 6400
Intel Core 2 Duo 1.66
2gb ram
80gb hard drive
so my question is, which windows version would you go with? Which has the least issues with the Traktor s4 software. XP, Vista or Windows 7?