Ok, started watching some movies on my PC again.
Hardware:
CPU: Intel i7 2600k
MoBo: ASUS P8Z68 V-PRO
Speakers: Logitech Z313 2.1
OS: Windows 7 Pro 64-bit
3rd party Codecs: K-Lite Mega
dxdiag: http://pastebin.ca/2086422
Got a few problems:
1) There is WAYYY too much bass on everything, even though as far as I can tell I've actually turned the bass pretty much off. (Unfortunately unlike my old Creative 5.1 speaker system this one has no bass dial on the remote.)
2) The Volume normalisation/leveling is totally defunct.