Try Vidomi, it's eqipped with a DivX player& encoder or ZoomPlayer 2.9. Vidomi is among the elite to make dvd2divx backups too. Vidomi DivX player will play Xvid as you can encode with an output file in Xvid format.
Asus K8N nVidia nForce3 Pro 250 GB, Athlon 64 3200+, Hitachi 80 gig SATA 150, Corsair XMS 1 gig PC4000, ATI Radeon Saphire 9600 Pro (256 DDR), Windows XP Pro (64 Bit),Lite-ON SOHD 167T,, Plextor PX-712SA,BenQ 1640.
These are the progs and codecs that you require to view xvids. First get 'DIVX 5.02' and install the codec only (the player is crap!),next install 'KOEPI'S XVID CODEC, then install 'FFDSHOW', next install 'AC3 CODEC' and finally 'ZOOMPLAYER'.
Google search for these five items (and add download to the search)then download and install. Enjoy.
P.S. Do not omit any of these five as they must ALL be on you pc to allow correct sound and video!