I am currently designing a software which has to control WIndows 2000/XP boxes remotely. Is there any API, which I can use for this purpose ?

The medium is LAN / WAN and communication will be through Wired channels and not Wireless. Basically, I am building a software like DameWare. I am finding a Exact API, to use for remote mangement, administration, screen and mouse event capturing, basically it should work like Terminal Services and Client. I have tested with Terminal Services API. My issue is, I should not start Terminal Services on any systems (my clients requirement ). For me it's hard to find How DameWare does this operation by using the Terminal Services API, without Startting the Terminal Services.

Thank you all in Advance.