Ok to stack components?

You're obviously asking about the heat. I think you'd be fine if you added a cooling fan or two and blew air across the components. You could place them behind the components, so they can't be seen. Coolerguys.com has all kinds of fans, including ones that come with a temperature sensor.

Without any extra cooling, I'd definitely worry the most about the receiver. The heat building will shorten its life, although tough to say by how much.

I really don't think that's a good idea. Where are the vents located on the components? Maybe you use some kind of standoffs between them?

I agree. I don't think it's a good idea to stack. We already know the receiver and xbox are susceptible to heat issues.

As a dish network user, I know thier DVR's (as well as all receivers) can get flakey when the temp gets up too high.

If you were talking about stacking a bunch of VCRs I would say "go for it".

I just think you would be safer looking for alternate audio pier for your equipment.

Grab some thick 1" rubber stoppers and put them in between the equipment to add a little more spacing. It will also help with air flow too.

I've done something similar until I get around to making the shelves for my unit. For now they're just spaced with small wood blocks. Definitely helps to keep things cooler than when I had everything stacked on top of one another.