Talking about PDA and laptop is always interesting. Which one will become your friend in your journey? Depend on your needs, right? A PDA is a better portable and lighter hardware than laptop. If you need to do some important things but you need a simple tool, PDA is your friend. But PDA could not do as many things as laptop. If you need to play some light games (or even heavy ones), laptop is the only choice for you (when you are outside your home sweet home).
Beside of this, laptop always has better specification. Some softwares will not work properly in your PDA (especially Adobe softwares because they need good memory). So if you think PDA is a better choice than laptop, think twice. Laptop has many extra features that you will not get in PDA. If you prefer larger monitor size, laptop is the winner once again. Do not forget that reading small fonts in PDA sometimes can be really annoying. For better internet browsing and word processing experiences, laptop has proved its worth.
But it does not mean PDA is not popular. PDA is a matter of speed. If you need to work faster, PDA is absolutely better. Laptop has larger space, better specification, can do many more things, but about speed, PDA is still better. Some of us only care about effectiveness, that's why PDA is still popular (in fact, it's getting more and more popular).
Actually, I prefer to buy a high-tech laptop than to buy a PDA. Yes, the differences between PDA and laptop are not big nowdays because laptops are smaller now and PDA has stronger performance. But for what reason do you buy a powerful PDA? If you want to play games (especially heavy ones like HALO 3 or CoD 4), of course a bigger monitor is better. I think at least a 17 "monitor is needed to get the best experience.