What would it take to run a service like XDRIVE.COM. I'm more interested on the Software aspects i.e Client Software, Server Software, etc

Well, to run something like that, you would need to most likely build your own protocol, and then build client/server interfaces to that protocol. You could base it on NFS, or maybe FTP.

Are you interested in simply purchasing a pre-made software package, or are you looking to program this yourself?

I'm really open to suggestions, I understand it might be technically possible to achive the above by using a client side FTP tool that works like the XDRIVE client, while on the server side utilizing the regular FTP services.

XDRIVE is programmed in jsp. :\

Very hard language to learn!..I have tried...and gone back to php, LOL :)

Well, there is no reason not to use FTP, as I believe it serves all of the functions you desire. I mean, it's simply a file transfer protocol, and you could adapt the server or client end to meet specific needs.

are you interested in running something like it? I have a PHP version of it I wrote a while back lying around somewhere.. I also can make a more up to date version of both their Desktop Interface and the xDrive service itself in Java/J2EE for you if you like.