Because I played halo CE with it.
Does any1 know how to program it so it'll work?
Or if it even does work?
thanks in advance

Anything is possible.
It's all about how you program each button on the 360 to work.

..But you wouldn't be using more than an analog stick and the A+B buttons..

Sounds like a simple concept that would take some time to make work. However, if you do get it to work, make sure to share it with us. I am very interested in if this is possible!

No, as Naota said, all you need to do is program each button, so it's pretty easy. Almost all PC gamepads come with some sort of software to program the buttons to fit games that don't natively support gamepads, so I guess it shouldn't be too hard. However RS isn't really a game, and I'm not sure how gamepads work in the Windows environment.
XBox controllers though, you would have to find some 3rd party software to program the buttons.

IMO, there's really no point to it because a large part to MMORPGs is typing. Oh yeah unless you got the new Chatpad thingy.

But when you think about it, Windows and the X-Box 360 control should be compatible, because you use a USB port for the Xbox controller. And they're both made by the same company. This starts me off on a whole tangent...if the controller was compatible would Halo 3 be compatible? If so, would you be able to use both at once and play Halo 3 on a computer? If so, could you get Xbox Live without having to get an internet adaptor for your Xbox? The possibilities are endless...time to start experimenting.

They are compatible

and of course halo 3 isn't compatible, it's written to utilize the xbox360, not a pc, which both run programs differently.