Windows NT Services
Various descriptions on how to write NT services in Visual Basic.
[>] AndreaVB
An excellent site with lots of information. The content ranges from low level programming using the Windows API, to ASP and COM components. You might get a bit lost in the design, but focusing on the center white section of the page will help a lot.
[>] How-To Run Your Application as a Service
[>] How-To Run Your Application as a Service: Part II
[>] INFO: Running Visual Basic Applications as Windows NT Services