If you know IP of a windows system and also you have a username and password. Then you can easily work in windows environment of that system from a Linux desktop provided that the remote system is switched on and is booted in windows. Also no one is logged in on that pc because only one person can access the pc at a time through this procedure.
There is a simple command u can launch from a linux terminal and that is..
[kulbirsaini@localhost ~] rdesktop -f [IP address of the remote system] [Enter]
[kulbirsaini@localhost ~] rdesktop -f 220.127.116.11 [Enter]
The full screen mode will appear and will ask for your username and password. Enter your password and experience that u r working in windows…
To return to the Linux press [ctrl-alt-enter] or go to the start menu and click disconnect. If this doesn’t work and you get some errors. Then you have to do some setting on the pc you want to access. Go to the pc and boot in windows and login as privileged user who has administrative privileges. Now click start and open my computer and go one directory up. Now right click on the my computer icon and click on properties. A new window will appear and on that window click remote and make sure that there is tick mark on the option “Allow users to connect remotely.”