Mercurial SCM (Hg) is a Distributed Version Control System (DVSC). More importantly, your code doesn’t know or care how it is being versioned. In other words, None of your VS solution or project files will be modified with a pointer to source control, and no *.scc files will be added in your code.
Interesting enough, Martin Fowler currently recommends Mercurial above the others at this point in time.
To get started, you will want to install the Mercurial Visual Studio 2008 SCC provider (for commits) as well as TortoiseHg, which is the tool you will use the most.
Check out my repository at http://palermo.codeplex.com with the getting started guide. If you already know Hg, the Hq repo can be cloned at https://hg01.codeplex.com/palermo.
For those who are new to Tortoise, Here is how I would go about getting the source:
I do have TortoiseSVN, TortoiseGit, and TortoiseHg installed. The experience is very similar among the tree, and they do not conflict with each other.