Thanks for the interesting thread. I tend to use Microsft's FolderShare to link to whatever files I need across my PCs, because it meets my 4 main criteria for use:
1. Good functionality (i.e., it does what it should).
2. Good price (i.e., FREEware or, at worst, reasonably-priced shareware).
3. Self-contained and independent (i.e., no forced dependencies on other, unnecessary or proprietary products).
4. Stability (i.e., it works, and has no annoying bugs - ß products are OK though).
I had not heard of DropBox or Live Mesh (mentioned in the comments above, so I went to the home pages for these two to run through the intros.
Result: I am going to try out DropBox.
WARNING! --- Start of rant ---
I went to Live Mesh first and clicked on "Take a tour", only to have a pop-up tell me that I had to "Install Microsoft Silverlight for a better experience on this site". Yeah right. Criterion #4 just fell over and I hadn't even got anywhere near the software I was interested in. Strike one. What beats me about this is why anyone in their right mind would force a dependency on an unnecessary product in order to communicate their sales benefits pitch. Experience shows demonstrably that, to be successful, marketing communications must operate at the lowest common denominator. They will never know how many people they just turned away by that single simple act alone.
On top of that the "Silverlight" pop-up wanted to access some new site - "agappdom.net" - that would not own up to who/what it was, so I became suspicious of it.
Live Mesh can get lost for all I care.
---End of rant ---