VLC is worth a try. Doesn't need any codecs (except for asf/wmv formats, I think), and can play nearly everything from DVDs and (S)VCDs (and derivates), through XviDs, DivXs and other mpeg4 formats downto some more obscure formats like RealMedia, QuickTime movs, h.264... It can play .bin/.cue images directly (without burning), so no more *VCD burning for non-standalone-player freaks
http://www.videolan.org/