If you have tried editing HD formats, like MPEG-4 (.mp4), or AVCHD (.mts, m2ts), you know it isn't easy, particularly on a slow computer.  If you're lucky enough to have a video editor that supports those formats, playback is very slow and jerky, and moving to a precise edit point is difficult.  This is because it requires lots of computing power to decode those formats on the fly, as you do when you're editing.

The beauty of converting to Windows Media Video (.wmv) is that you can edit it on any version of Windows with any computer that has a reasonable amount of power -- even many laptops -- without experiencing these difficulties.  Once you have used the procedure detailed in this video, you can be set up with a template specific to any camcorder you have.  You can convert all your video in a batch, and edit movies of superb video and audio quality.

Alert user texas123 pointed out that a new version of Microsoft Expression Encoder has become available -- Expression Encoder 4.  I downloaded it, from this link:

http://www.microsoft.com/expression/try-it/Default.aspx

Use the button on the bottom left to get the free version.

They have done some functional separation that some might consider a simplification of the user interface (I don't), but apart from that this version is functionally almost exactly the same as Expression Encoder 3, so you can still use it in precisely the same way as the video describes.  It might be worth picking up Expression Encoder 4 just for the likelihood that you will pick up some bug fixes.