Frank:
InstantRails is the best way on Windows… I’m currently hacking IIS but
it’s a really big pain.
Rails is pretty easy to set up on a Linux / unix environment. That’s
because nobody here other than Curt H. cares about Windows (I’m just
kidding, you guys!) Seriously, though… I don’t think we’re to a point
where I would be completely comfortable putting a production Rails app
on Windows.
If I were you, I wouldn’t worry about this until you have a couple of
working apps that you want to deploy. There are lots of ways to deploy
multiple apps, but I think you have to understand how Rails works. It
took me a bit to get it. Look at the wiki article again after you’ve
got some Rails experience and it should come a bit easier.
Or you can just go pay for some app hosting 
If you’re still interested in setting up Apache for multiple apps, let
me know where you’re getting stuck and I’ll attempt to assist you. Be
aware that you want to ensure that you’re using FastCGI with Apache,
because otherwise you’ll be really unhappy with Rails’ performance.
Additionally, there’s the newer SCGI (which InstantRails uses) and this
is a bit more tricky for multiple apps.
-Brian