System.Security.Principal.WindowsIdentity.GetCurrent().Name will get you the user that the service is running as, but services generally run under special user accounts like "Local Service". Services also start before the user logs on so you can't just set it to run under the currently logged on user, because there might not be one. Services aren't really meant to be tied to the logged on user. What would happen if you had two users logged on at the same time (which can happen). Perhaps you should consider making your app a normal client based app (but with no GUI) and stick a short cut to it in the start up menu. You should also probably be using windows authentication instead of getting the user name.
Simon
