I use Vault for personal/side work. It is SQL Server based, so you also need a license for it. I've used Subversion at work. I don't really have a preference for either one. But the Tortoise shell for Subversion is very nice. It integrates into Windows Explorer, so check in/out, etc is just working in Explorer.

>Thanks Craig. Which one do you personally use the most and /or like the best?
>Alex