Ever since I first downlaoded this I have used it exclusively. It plays virtually everything, and doesn't eat up resources. It doesn't really have any fancy bells or whistles, but is capable of playing everything.
My Desktop: <A HREF="http://Mr5oh.tripod.com/pc.html" target="_new">http://Mr5oh.tripod.com/pc.html</A>
Overclocking Results: <A HREF="http://Mr5oh.tripod.com/pc2.html" target="_new">http://Mr5oh.tripod.com/pc2.html</A>
I use MicroDVD. Don't know if it's still around, or free, because I have a two year old version I refuse to upgrade. It's simple and stable and a nice interface. Plays all media types just fine.