One thing that stands out for me is the use of externals and a main drive. Neither are optimal. Ideally you want a minimum of three internal drives, with five being a better basic arrangement.
How about your system and video project specs?
Intel Core I7 @ 2.6 Ghz
3Gb of RAM
ATI Radeon 4850 GPU 2Gigs of VRAM
Realtek High Def Audio
238 Gigs of free space on internal drive/937 gigs of free space on external
Projects Settings: Using Premiere preset for Digital SLR 1080p@30fps
1st, while it MAY work, Vista is not a supported version of Windows
2nd, 3gig of ram is barely enough to load Vista and the program, with virtually nothing left over to actually DO anything
3rd, DSLR video requires a STRONG computer... your configuration really is not very strong
This message has a really good graphic about requirements - http://forums.adobe.com/thread/810750 - click the picture to enlarge to readable size
So my question is, why won't it even play audio files in Premiere. And again...this same issue happened with CS4 but was fixed with an update.