The 8xx series is going to run quite a bit hotter from what I know, and isnt as fast from what I've read.
I received an Intel Retail Edge bundle, It came with the 820D and an Intel D945PSN motherboard. It is plenty fast for what I use it for paired with 2GB DDR667 and a Radeon X1800 XT. If you're looking for more of a "budget" system, and want to stay with an Intel Dual Core set-up you won't be disappointed as the 820 is hardly a slug.
Cooling is another issue. With 6 80MM case fans, and video card cooler, my CPU sits @ about 48C-52C idle. Using the TV tuner on my AIW or playing games seeing 62C is not uncommon. Before I added more case fans I hit 70C occasionally. This is due to my small ATX case, the fact the mounting mechanism for the stock HSF sucks, a hot AIW video card and the fact that my dorm room is almost always 75F plus (Case temps vary from 92-110F depending on what I am doing).
Don't know if that helped, but thats my expirience with an 820.. feels quick, always worrying about the temps. I would only recommend a current Intel dual core set up if you find a real good price like I did.