7.1 HT under about 3k

Lots of good advice here. I think that the 2 extra speakers in the back that turns your system from 5.1 to 7.1 should be viewed as "complementary." In your system, they are least important by a very very long stretch. So do not spend money getting two extra speakers if it means cutting somewhere else in your system.

Joncourage, I might be missing something here, do you plan to use the amps in the Onkyo?

Bruceomega, you are right. The thing is that depends as well on the room dimensions, the room that i Have with 5.1 is w 16.5 and 20 feet l.
For me 7.1 in this room makes no sense due to the closeness of the speakers, and my budget, he, he, he.
Joncourage, if you want to buy it perfect, but really go first with a good 5.1 (7.1 processor) and then add with time and money the two extra speakers and the amp

Javierschmidt,

FWIW, my 7.1 set up is in a room which is approximately 13' x 17' x 9.5'. Both my side speakers and rear speakers are about 7' away from the primary listening position (they're suspended from the ceiling, pointing down and toward the listening position). My intuition says that is a bit close, but my room layout doesn't provide any flexibility. Fortunately, it works.

There are times when 7.1 is not a good choice, or even impossible such as when the listening position is flush against the rear wall where you don't have room behind you to place the rear speakers. AFAIK, room size itself should not be a determining factor, but room layout can be, just as the cost of an additional two channels can be.

Cheers
Bruce