We don't Salute You!
For the next 100 posts whining about how this isn't exactly like forwarding an Xterm over an SSH tunnel (think about how stupid that is for a second)... X IS NOT NETWORK TRANSPARENT
What? That a lie! 1985 sez X is network transparent!
Well guess what: Modern versions of X are *not* network transparent anymore because to use any of the modern features of X that make using a modern Linux desktop even remotely enjoyable, you are breaking the classic backwards server-client paradigm of X. Sure, there's still a fallback mode for transferring data over networks, but lots and lots of modern features that you expect in a modern desktop GUI break in the process, which is *not* transparency, but is instead more of a network fallback.
Frankly, having tried to use both X and RDP over real connections using the real Internet, I'd take RDP any day of the week. I still remember the finger-pointing amongst developers of different projects when I pointed out that packets were being sent over the network each and every time my cursor blinked. Get over it guys, 1985 wasn't the be-all end-all pinnacle of graphics development.
Still don't believe me? How about clicking the link to Dan's talk about X where he says the exact same thing I just said. He's only been working on X development for over 10 years though, so I'm sure that some guy who sorta got X forwarding working over a gigabit link is much much more informed that he is....