I wrote a long response yesterday, only to have it get lost in the server reboot.
I've bought both HTIB systems and various component. Some thoughts on HTIB.
First, they do a reasonable job of solving a limited set of problems at a low cost. The problem they solve is improving the sound from a TV and adding a DVD player. If that is all you will need, then go for it.
They generally don't have a lot of expansion capabilities beyond that, so if you are planning on adding a BluRay player or satellite box, you will need to shop more carefully.
HTIB systems are often difficult to upgrade. The amplifiers are designed for the included speakers, so a speaker upgrade is often impossible. The speakers themselves are small and usually have an uneven frequency response. The subwoofer is invariably a small bass reflex design with a 60 watt or less amp. This will lead to boomy bass without a lot of definition.
I'd look at building a modest component system. The Onkyo is a good choice. I have a 605 currently in one of my systems. There are some good HT speaker systems out there from reputable speaker manufacturers. I'd avoid the ones that come with subwoofers for reasons stated above and budget for a good one from a manufacturer known for quality subs.