SD is Standard definition... i.e. normal DVDs, freeview, non-HD sky channels. I take it that this is going to make up the bulk of your viewing. On the PX80, SD is better because it is not a fullHD telly. FullHD tellys i.e. the PZ range, tend to make SD look a bit worse than the HD ready PX series. Also,as I have said before, I don't think fullHD is worth the extra money you have to spend unless you are going for something over 42", when you will see the benefit. The Onkyo 605 is a really good peice of kit. I bought one, as did many others on this forum, and WHFSAV gave it a product of the year award. The 606 would be worth a look if you need more HDMI connections, the rest of it should be the same, but we are all waiting on a review to find out. The monitor output is a composite output for easy setup as the Onkyo has an on-screen display for its setup menu. This can be done via HDMI aswell. The Onkyo has HDMI inputs, a HDMI output and the same in Component. It means you can use the Onkyo as a HDMI switcher. The HDMI on the Onkyo supports HD audio aswell. It is just an option to consider, ther is nothing to stop you from just running HDMI direct to the telly and digital audio to the amp using the coax or optical. You could always have a read up in the manual which should be available from the onkyo website, and it tells you how to set things up in a number of configurations with different sources.