Hi. While changing your program to explicitly support the Windows Services API is certainly an option, simply launching it from a wrapper may be a better choice in many circumstances (when you don't have control over the code, don't want to deal with the complexities of the API, etc.).

The free XYNService at CodeProject (http://www.codeproject.com/KB/system/xyntservice.aspx) is a fine choice to run a console application as a service. Check out AlwaysUp (http://www.coretechnologies.com/products/AlwaysUp/) if you can afford to go with a more fully featured, commercial solution.

Good luck!