Integra/Onkyo is right up there with Denon, Yamaha, Harmon Kardon, Pioneer, etc.
Integra is owned by Onkyo. They are basically the same company but Onkyo is the consumer line which you will find in Brick and Morter stores like Circuit City and many other internet authorized dealers.
Integra is the high end custom installer line which you will have great difficulty (from my experience) finding anywhere but custom installers and select higher end Audio Video retailers.
I have compared specs on both lines and have owned Onkyo for years. Integra has better specs but cost more then Onkyo. However, Integra comes with a 3 year warranty on everything they sell with the exception of one or two items. Onkyo, on the other hand, has a one year warranty on everything they sell with the exception of their receivers which have a two year warranty.
You can visit both of their sites and do some comparrisons between two similar prodcuts. A good comparrison is the Integra DPC 8.5 DVD changer and the Onkyo DV-CP802 DVD changer.
Here's the Onkyo DV-CP802 6 Disk changer:
http://www.onkyousa.com/model.cfm?m=DV-CP802&class=DVD&p=i
And here's the Integra DPC 8.5 6 Disk changer:
http://www.integrahometheater.com/model.cfm?m=DPC-8.5&class=DVD&p=i
Hope that helps.