(I'll keep this one a little shorter)
If you watch a Blu-Ray player, your regular DVDs will probably look about the same. The upconverting technology in your Q80 has probably been improved in the last several years to probably offer a noticable, improved difference.
Your real benefit will be Blu-Ray movies. Now, your panel can accept a 720p signal, so you'll want the native resolution from the Blu-Ray player to output at 720p. I believe the default is 480p out of the box, so bump it up in the Setup Menu in the Blu Rapy Player. You won't be taking advantage of the possible 1080p picture, but you'll still get a very clear, worthwhile picture at 720p - a significant improvement there.
To keep your surround sound options, since Blu-Ray does have that, what you might consider is making sure you have an optical or digital audio in on the back of the Q80. If you do, just patch the audio from the BDP-xxxx BluRay player to the HT-Q80 via optical.
Does the Q80 have an optical out? I have specs, but I want to clarify to make sure it exists for that - definitely something to consider.
Keep me posted!
I own a Samsung LN-S3251D - http://reviews.cnet.com/flat-panel-tvs/samsung-ln-s3251d/4507-6482_7-31787622.html
I also have a Samsung HT-Q80 XM Ready Five-Disc DVD Changer Home Theater System (5.1 Channel) - http://www.amazon.com/Samsung-HT-Q80-Five-Disc-Changer-Theater/dp/B000F7684U/ref=pd_rhf_p_t_3
If I purchase a Blu-ray player for this system will the picture quality (and overall cinematic experience) be any better than what the HT-Q80 is providing?
Thank you in advance for your time and thoughts regarding my dilemma.