I'm not really sure, but I think that compaq was on the verge of death, and got bailed out by HP, but compaq may just drag HP down with them.
As far as dell goes, I think that they will back off into the server market, and cheap comsumer models, but even then, they may just abandon all comsumer computers.
Gateway, in my eyes, is screwed. They offer the same as everyone else, but without as much reliability.
Sony may be the only other company to make good, decent, pee-cee's. They are Apple's main competitor, and, as Jobs says, "They copy us like crazy!"
IBM is going to hack their consumer market.
It's all about selling the computer with the most, for the least. People see big specs, and a small price, and say, "this must be good". Unfortunatley, they screw themselves over when they do that. You get what you pay for.
If there was a Mac in every computer store, Apple would have a lot more marketshare. I've seen computer stores with titanium powerbooks, and ibooks, and cinema displays, and people are just impressed. They are like "wow, this is a cool computer." They blow away all of the pee-cee laptops.
To stay alive in the computer industry today, you have to innovate (Apple), or copy like hell (dell, sony, hp, compaq, gateway, emachines...)
besides, you can always build your own pee-cee for less, and if you want a laptop, Apple is the way to go, hands down.