It really depends on what you plan to do with it. Personally, I do enough typing (a lot of it here on Fluther) that a netbook makes far more sense merely because of having an actual keyboard built into it. With the iPad, you either need an external keyboard (which you would probably have to buy) or deal with a virtual keyboard that is pretty tiny and, due to the lack of give in the “keys”, rather uncomfortable after a couple of paragraphs, at least if you are used to typing on an actual keyboard. For mere surfing though, the iPad may suit you better.
The iPad 2 can shoot 720p HD video from the rear camera while most netbooks have more basic video capability more suited for web-chatting like the one on the front of the iPad, and you’d have to be a little ingenious and fairly desperate to try much more than chat with it.
A Netbook closes up in such a way as to protect the screen though, and given the drop test results I’ve seen for iPads and iPhones, anything that protects that glass is a good thing. Battery life on a netbook seems to average 6 hours or so in real-world use; I’ve found that to be plenty long enough unless you are the type of person who hates charging things every night. Then again, that figure varies wildly from 2 to 10, depending on the netbook and battery. See below
If you already have a laptop of your own then the iPad is the way to go. If you want to shoot HD video and don’t already have another way to do it (digital camera, smartphone…) then the iPad is also the better option. If you want something that can actually be used as a real computer then the netbook is far better, if for no reason other than more storage. When I had mine, I had pretty much everything I had on my desktop system in it; no iPad is capable of holding just my RPG sourcebook library, let along all of my music and videos as well since they max out at 64 GB and cannot use external storage.
One last thing to consider; as easy as people claim iPads are to use, you already know how to use a PC so a netbook will not require learning any new skills. Sure, iOS isn’t hard to learn since it really can’t do much beyond the basics, but if you feel that your brain is already full then familiarity may not be a bad thing.
@downtide My old 8.9” Aspire One only had 2–3 hours, but that was because I opted for the smaller, lighter 3-cell pack in order to keep the thing svelte. Many of the newer ones come with 6-cell packs and more efficient CPUs though, and those generally go from 4–10 hours, depending on the make/model.