I built a new system at the end of January and bought Vista Home Premium 64bit for it and I would do it again. I haven’t had any problems although I have had issues. If you have XP computers on your network, getting them to talk to each other and share files/directories is a little trickier than on an all XP network. The double dammed Windows Explorer steadfastly refuses to maintain folder view settings without some advanced work.
You will have to get used to a new OS but I don’t see the point in holding on to XP any more.