New HTPC Build Suggestions

I currently have HTPC build below. I am looking for a newer, faster and slimmer system that will be able to have DTS-HD M, Dolby True etc. Some stuff I can still use, but a much slimmer case and audio is a must. Any suggestions? Looking at being in group 7 with a slimmer case.

MOBO:
Asus P5N7A-VM

Processor:
Intel Pentium Processor E5300

Drive:
Western Digital 1 TB Caviar Green SATA Intellipower 32 MB Cache

Optical:
LG Electronics CH08LS10 LightScribe SATA Blu-ray Combo Drive

Case:
Antec NSK2480 w/ 380W PS

RAM:
Did not order; 4GB leftover from another PC