Question : Services to rent CPU time on Windows

Hello Experts!  I have a windows app that does a bunch of CPU intensive computational work.  Unfortunately, the work cannot be distributed/chunked up into smaller sets.  At any given time I want 1 to 10 of these apps running, each on separate machines.  Because there's lots of downtime, I want to use the rental model - I spawn the machines as needed and take them down when not.

So far I've tried to use Amazon's EC2 service, but found that when I emulate Windows inside an image, its incredibly slow.  My calculations take forever to process.  Are there other services I can try?

Answer : Services to rent CPU time on Windows

This doesn't really follow a standard web hosting model.  In teh Amazon service, I can spawn up to 15 computers and I only pay per hour of time used.  I'm looking for something more flexible than a standard hosting company would offer.