I have developed my own shopping card software that allows visitors to
my website to select items that they want to order.  I also have
software to collect the address and credit card information and
generally complete the order, but I've encountered some problems and
want to use a professional service.  Here are my requirements for that
service:

1) I want to use my shopping cart software -- I do not want to use a
3rd party shopping cart software.

2) When the user is ready to check out, they will be sent (relatively
transparently) to a 3rd-party's secure server.  At that server, over a
secure https connection, they will enter their shipping and billing
address, and their credit card information.

3) The 3rd party *must* use Microsoft's IIS webserver.  I have my own
reasons for wanting this, so don't bother asking why.  If they use
Apache or Netscape or anything other than IIS, then they won't do.

4) The 3rd party will authorize the user's credit card for the amount
of the sale, but it will not be charged.  I don't believe in billing
credit cards before the items ship.

5) When I ship the items, I will notify the 3rd party (preferably with
some batch method) and the credit cards will be charged.

Basically, I need a service that collects user information, authorizes
CCs and charges CCs using Microsoft's IIS webserver.

Can somebody point me to a company that provides this service?