Easy AVI/MPEG/RM/WMV Joiner - description from Softdepia.com:
Easy AVI/MPEG/RM/WMV Joiner can help you join multiple AVI, MPEG (MPG) or RM (Real Media) and WMV/ASF video files into one large movie file. You can add an unlimited number of video files as you like to the list and easily rearrange their order if needed. With just a few mouse clicks, you can enjoy your movie clips without interruption.
Easy AVI/MPEG/RM/WMV Joiner is a "Free to try" program. You can download and try it for an evaluation period.