Remote Desktop Protocol (RDP)
Most linux distros now come with the rdesktop command which allows you to connect to PC's or servers (even across domains) that are running the RDP service.
I am actually writing the documents on this site right now with Dreamweaver MX 2004 in a remote desktop session with my Windows XP Pro system at work on our Windows 2003 domain.
rdesktop -d domain_name (if any) -u sgt-d -g 1280x1024 126.96.36.199:3389
You can pass along a password too, mine doesn't work because it starts with an exclamation point (!), so I don't attempt to include it when connecting.
Usage: rdesktop [options] server[:port]
-u: user name
-c: working directory
-p: password (- to prompt)
-n: client hostname
-k: keyboard layout on server (en-us, de, sv, etc.)
-g: desktop geometry (WxH)
-f: full-screen mode
-b: force bitmap updates
-L: local codepage
-A: enable SeamlessRDP mode
-B: use BackingStore of X-server (if available)
-e: disable encryption (French TS)
-E: disable encryption from client to server
-m: do not send motion events
-C: use private colour map
-D: hide window manager decorations
-K: keep window manager key bindings
-S: caption button size (single application mode)
-T: window title
-N: enable numlock syncronization
-X: embed into another window with a given id.
-a: connection colour depth
-z: enable rdp compression
-x: RDP5 experience (m[odem 28.8], b[roadband], l[an] or hex nr.)
-P: use persistent bitmap caching
-r: enable specified device redirection (this flag can be repeated)