I don't think you'll be dissapointed with your BV5. I have the BV5 non HD and I'm really chuffed with the picture! (not as good as my MX8000, but as it is completely different technology you can't really compare) All I know is that my BV5 still outshines many Plasma TVs I see on the high street even now!
Your Apple TV sounds like it will work (the "new" ATV has only been out a couple of months or less and is a little black box, so yours is likely to be one with a built in HDD). As far as using the ATV with your BV5 you should have no problems. The "Apple Remote" setting on the inbuilt BV5 STB controller works the ATV. I'm not sure about HDMI/DVI connection as I have had to use composite via a scart socket.
The BV5 has only one STB controller IR out, so if you plan to control other items such as Freeview Box you need to buy the B&O "Y" splitter and a second IR emitter. The BV5 can only control 2 items. The IR emmitters are colour coded gold & silver and you have to have one of each. The ATV really suits the look of the BV5 and I have mine between the Base Cabinet & the TV.
I love my setup and yours with BL8000's should be great. I use 2 BeoLab Pentas. and listenning to my music collection on the TV/Pentas sounds fantastic.
Stoobie