Computer help: Acer HDMI Problem

Acer HDMI Problem

I recently purchased an Acer Aspire M5640 AM5640-E5407A (long name I know, but that is how it is listed on TigerDirect.com) Here's the link if it helps:

http://www.tigerdirect.com/applicati...1&body=QA#tabs

My problem is the HDMI port. First, the computer came with no documentation other the the warranty and a fold-out pamphlet with arrows pointing to pictures of the components. No description, no system info, just arrows. I am using my 56' living room TV as the monitor at the moment, connected by RGB cable . I've gotten everything set up and I want to watch a HD movie, as it came with a Blu-Ray/HD-DVD combo drive, and it has a HDMI port on the back, so I'd like to use it and get full HD results and audio without a cable jungle. Unfortunately just plugging the cable into it's respective places and switching to HDMI doesn't do the trick. For reference, the HDMI port is on the motherboard, not the video card. I tried to go through the ATI catalyst control center to see if there was a way to divert video, but no luck. I've tried ACER email tech support, but they refer me to manuals that don't exist, seemingly even on there website. They have an M5640 section, but not my specific E5407A. The other systems are all dual-cores with different video cards and other dissimilar components, and mine is a Quad.

System specs:
Vista Home Premium
Intel Quad-Core Q660 (2.4 Ghz)
3GB Ram
ATI HD2600 Pro (512)

A few people on the Tigerdirect page have popped up with the same problem, and similar lack of results. I'd really hate to have to get a brand new video card with built in HDMI just for that purpose. If you can't help, please refer me to a forum/resource that may be able to.