Remote administration without install on client

Is there a remote administration software out there where I can remotely view another computer's desktop... without having to install the program on that machine?

Not that I know of..well there is remote desktop, however you take complete control of the connected computer so other users can not use it.

Yeah remote desktop could work but it needs to be enabled on the computer and is only available XP and I believe 2k Professional lets you do it too plus all the Windows Server versions from 2000 and up.

I believe that you can only remote desktop into Windows 2000 if you are running Terminal Services on the machine that you're trying to connect to.