I like TFS: http://tfs.visualstudio.com. Of course, it's more natural a choice if you use Visual Studio.

I use C# 2010 Express. Will that work with TFS? Or will I need C# 2012 Express?
Checking out git as well. This is the 2nd time someone recommending it.

Originally posted by Davio
I use C# 2010 Express. Will that work with TFS? Or will I need C# 2012 Express?
Checking out git as well. This is the 2nd time someone recommending it.

You can use it with any of the free Visual Studio 2012 Editions: http://tfs.visualstudio.com/en-us/pricing/information/

One good aspect of it is that you can define tasks and assign them to users and monitor progress, etc, other than just keeping versions under control. Use for a team of up to 5 people is free.
If you use Visual Studio, I think you will enjoy the integration. Everything works pretty much naturally. Like Huw, I use it at work, but am using it for personal projects as well.

I use Subversion at work and its ok. Use GIT outside work and its fab.