I think you have two options, really:
Subversion. It's easy to setup etc, and free. I like VisualSVN, which is $50, and worth atleast 5x that much, but you can use Ankh (free, OSS) or just use tortose (windows explorer plugin, OSS, free).
Once you have tortoseSVN (VisualSVN needs it too) you can make local repo's, or use a remote one, eg VisualSVNServer (also free), or personally, I have mine hosted with my websites at dreamhost :)
Another option is SourceGear Vault. It's GREAT if you have a windows-based server somewhere (it's SQL 200x + ASP.NET based, including SQL Express Edition I think), and it's free for one user. Very good if you are used to SourceSafe or TFS, and it can work in the SVN/CVS checkout-merge-commit way if you want to (not the default, but easy to change), or just use the check out - lock - check in way like VSS.
You might have heard Eric Sink of SourceGear on the Stack OVerflow podcast the other week - same company.