Yeah, truly the whole question in the header. Is there a way to use Windows 7 offline sync (which we know from network mapped drives) with a external usb hd?

When not, are there similar built in tools or good third party tools?

My scenario: I want to buy a ultrabook with SSD which is mostly limited in space. So I'm going to put all files to a external HD and only store current projects on the local SSD. Let's say I have to change project. It would be easy just change sync folders and have the second project synced to my hd too.

With network mapped drives it's such easy. Paths do not differ if the drive is offline so in most situations you don't take notice if the folder is offline. And you only have to activate offline file for the folders you courrently need for work. So is there a similar solution for usb hard drives?