I've done this with my setup, and the dual-boot works
fine. In fact, the Ubuntu setup gave me the option, all I had to do was OK it.

Is there some way to change the order the selections show up
in? Instead of defaulting to Ubuntu, is there some way I could have
it default to Windows XP?

I know, all y'all are asking,"WHY???"

Well, if I was to do that, then I could put Ubuntu on the
home computer, and if I wasn't there, my family could still use the
machine with something they are familiar with.