Tools for converting physical servers to virtual machines

Microsoft's own tools for converting live machines to VMs are really not very good from what I've seen. They're clunky to use and require that you go through a multi-stage conversion process which interrupts work on the original server. That said, they're free -- and if you don't have much of a budget to work with, they may be the only game in town. I've looked at some other migration solutions, such as LeoStream P>V Direct 3.0 and PlateSpin PowerConvert, which are a lot more seamless -- but also that much more costly, and typically charge per system converted. If you can spend the money to use such a tool, look into them.