Strange question at least unless you have the projets able sucessfuly hosted as on linux and windows as well. Windows always more expensive, but at the same time not often used
Most of great VPS providers like hostV.comVpsland.comeuroovps.com have specialization in Linux technologies and I have to say that that can explain many things:
Most web applications are written for linux.
Linux is less expensive.
I think those 2 issues are the main ones.
You know sometimes is better to use a semi-dedi. Very often the clients don't know how much CPU and bandwidth they'll consume and pay more than necessary. I'd advise you to look at Webhostingbuzz.com semi-dedis. Think that's what you are looking for.
I second HostV.com as this company uses the latest server virtualization technology. Double RAM (limited time offer) and a diacount - 50PROMO that gives a 50% discount on their services.
Some questions: What will you be hosting? What programming language/environment will you be using? What databases are you going to be using? What authoring tools will you be using?
The above answers will help in determining what direction to go in.
Everything depends on the software that is needed to be hosted... Since some soft is supported by windows platforms only, it is needed to search for a corresponding host.
For windows hosting I prefer aspnix.com - they are narrow specilized and thus may grant good rate of services.