I have windows xp;  I have recently just downloaded from this website the 1). Virtual Dub 1.6.3; 2.) Koepi\'s Xvid 1.03; and 3.) Divx 5.2.1.  I went to the instructions on \'AVI join with virtual dub\'.  I am trying to join the two files so it doesn\'t stop.  I followed the instructions, but when I get to the point of opening the file I want,  an error comes up when using either or the codecs that I downloaded.  I downloaded 1st the Xvid. Here is the error message that I am receiving:

VirtualDub error
  couldn\'t locate decompressor for format \'MP43\' (Microsoft High-Speed MPEG-4V3)
   VirtualDub requires video for window (VFW) compatible codec to decompress video.

What am I missing or what do I need to do to get the virtual dub to work correctly?

Thanks in advance