audio & video problems

[Paul Kaplan]

If I use VLC media player, I have no problems viewing or hearing the audio 
track of mpg, avi, or wmv video files.
If I use Totem, I can see & hear wmv files, but there is no sound associated 
with mpg files and for avi files I get an error on avi files saying the XviD 
codec is not handled.
If I use gxine, I can see & hear wmv files and again there is no sound 
associated with mpg files and avi files appear to open, but the progress bar 
advances in a fraction of a second and then the playback appears to end.

I have the w32codecs package installed.
Can anyone figure out why Totem and gxine are unable to correctly play mpg and 
avi files?
Paul