The problem with any iPad competitor, be it from MS, HP, or anyone else, is that right now it's looking like (from whats been shown so far) too little too late. Apple is so far out in front with the iPad now that any notion of putting something out there that looks a little like the iPad is simply repeating the same formula that put the iPod way out on top of the so-called iPod killers from the first half of the decade. Some of the biggest names in technology, including Sony, Microsoft, etc., put out their half-baked, third-rate mp3 players thinking that if it looked a little like the frontrunner, suckers would buy the thing in droves. The results were as predictable as they were obvious. Apple could have had some serious competition in the early days of the iPod, but no competitor took the time to understand why the iPod was a success. No one. Apple was effectively handed the market for portable mp3 players.
I have a feeling this is going to be yet another episode of utter competitive stupidity. If MS or HP or any of the usual suspects puts out something that's based on what we have seen so far - forget it. Game over. Apple wins.
If, on the other hand, Apple's competitors go back to the drawing board and think about what the next stage will be in the evolution of the iPad, and hits the market with that before Apple does, then maybe, just maybe, they would have a chance.
But it ain't gonna happen. The competition will do what they always do, put something out there that looks a little like the iPad and leave it to marketing to do the rest. Because they are too stupid and lazy and cheap to do anything else.