Media playback - surround sound oddity

Naf

Basically I'm confused why the rear speakers on my surround sound don't normally play any sound.
It's just a PC system from Logitech, plugged into my sound card from 3 of the 6 colour coded 3.5mm jacks (is that SPDIF?).
When I use the 'Soundmax Audio Wizard' (manufacturer supplied software with my motherboard) it recognises the correct speakers, and plays the test noise to all of them.
When I play music through iTunes it plays to all speakers (it may not be any real form of surround, but it uses all the available speakers and sounds better)
When I play video files through QuickTime it also uses all the speakers.
When I play a DVD through Power DVD it also uses all the speakers.
Problem is that most of my video files are Xvid and so play through Windows Media Player, which usually refuses to play sound to the rear speakers at all.
I had been assuming this was because there is no surround sound information encoded in the files, because sometimes WMP does play to all of the speakers. But even files that WMP doesn't play to the rear speakers, QuickTime does. But QuickTime can't seem to cope with Xvid (despite me downloading the codec it linked me to) and doesn't show video at all, and the audio gets garbled.

Anyone have any idea how I can smooth this out? I'd love reccomendations for a better media centre/player even; one that will play all my media, regardless of encoding, and make use of all the speakers regardless of whether there's surround sound encoded?

bengalknights

Try VLC player

Naf

Seems to work a treat, thanks. Plus discovering several extra features I like.