Offline Folders

I recently became interested in the offline folders feature of Windows XP. I hadn't been very pleased with it in the past because I had several gigs of information that it would try to sync, but now I'm in a different boat. I'd like to have a single folder that I designate as "Make available offline". That way, when I work on a file in this folder from my desktop I can open my laptop, sync automatically, and be on my way for the road.

Unfortunately, when I right-click the My Computer menu option in the start menu the "Make available offline" menu is checked, but also greyed-out so I can't change it.

Can anyone help me make a single folder of my choosing available "offline"?