VW reccommends for the earlier year bugs to be changed at 60k. but you can go up to 80k... but that's supposedly stretching it.
i just had mine done a few days ago and i'm a few hundred miles shy of 60k miles... but i'm moving soon and i got a kiiller deal because i know people that work at VW.
at any rate, get your water pump replaced at the same time. will save you a couple hundred dollars down the road in labour alone when it does, in fact, go out.