I can only partly answer your question, because I have the same question partly.
-The system will play movies and upconvert the DVD files when you play DVD's from your computer's DVD drive, because your resolution from your computer's video card should be capable of 1920x1080 (if not a BluRay drive will be worthless)
-If your rip your DVD's to your hard drive and play them, then they are passed through the A/V receiver and the video will be upconverted
-There are not constant resolution issues with an HDTV as a computer monitor, if you plan to use it for movies, gaming, etc. If you intend to do word processing you will probably get annoyed.
-The bluray drive is cheaper than stand alone, but I do not now about the audio passing through the A/V receiver
On to adding my own question as well:
I was hoping to use the Onkyo 6100 HTIB setup with my PC, HD cable, and DVD player in and output to my Samsung 61A750. My PC's onboard audio is 8 channel, and I have it routed through my graphics card to an HDMI output. See EVGA-790iFTW motherboard and GTX260core216 video card. I use an internal BD-rom drive to watch BluRays, and I was hoping that with this receiver I could take advantage of the uncompressed audio tracks within most of today's BluRays.
I know for sure that my PC's HDMI source as seen by the receiver will be fullHD video, but will the audio processed by the receiver be trueHD? My onboard audio has a six pin output connector located next to the PCIe x16 slot on the motherboard, and the GTX260 video card has a 2 pin S/PDIF connection on top which is how the audio is sent through HDMI. Will this be received as a bitstreaming HDMI source, and how will this affect the uncompressed audio tracks played from the BD-rom?