>How can I start an application in VFP6 as a NT-service?

There's a tool called SRVANY available as part of the NT4 resource kit. There's plenty about it at the MSDN site with examples of making a VB app a service.

I quote:
The Windows NT version 4.0 resource kit provides a tool called SrvAny.exe for this purpose. This tool is actually a simple Windows NT service, which when started, spawns any regular Win32 application specified in its startup parameters. Please see SrvAny.wri in the Windows NT 4.0 resource kit for documentation of this tool.