Does anyone know of a VS.Net 200X to VC 6 project file conversion tool?

We have lots of clients who haven’t moved away from VC 6 yet. At present we need to maintain all our projects in a VC 6 compilable form. The easiest way to do this is just to use VC 6 as our primary development platform for C++. If we had a tool that allowed us to back port VS.Net 2003 projects to VC 6 then we could maintain the projects in the latest format and back port as required. As it is, we need to maintain them in the earliest format because we know that the newer compilers will always support upgrading from old to new… So, for us, at least, if MS provided a tool that took a project and converted it to an earlier compiler then we’d migrate to the new versions faster… As it is we can only migrate fully when the last of our clients (or potential future clients) gives up on VC 6 …

Is there a 3rd party tool available? We’ll pay money…

[Updated: the title of the post was wrong ;) I needed a new file format to old file format conversion not an old file format to new file format…]