So, since you want a free solution here's my thought on Dropbox vs the Microsoft soluiton.
Dropbox gives you 2GB of storage, nice client apps for multiple platforms, plus web access to your files. You can share those files with whoever you want. A down side for me is that everything you want to syncronize has to be in a single folder... and sometimes that's not possible.
Microsoft has Live Mesh 2011 which gives 5GB of storage if you use the web. Let's say you whant to syncrhonize your home and work computers, you don't need the web for that so you are not using any of the 5GBs. Live Mesh has also a cool client app and you can synch up many folders which do not have to be child of a specific common folder. But, once a folder is set for synchronization you can't exclude a child folder... that's a down side specially if you are synchronizing source code.
Microsoft also has SkyDrive where you have up to 25Gbs of storage but you can only aceess thru their web page. They don't even have any API (yet)
Me? I use all of them :)