One of the things that really bugs me about IIS is that you can't run multiple web sites under XP Pro. I guess Microsoft assumes "Pros" will have an XP Server box for every developer. This is the main reason I use Apache on my dev box and my laptop.
A coworker pointed me to an ISAPI filter called MultiSite. You can find it here. I haven't tried it yet, but it seems like the perfect solution.