I don't know if things have dramatically changed, but back when I bought my netbook about two years ago (ASUS EEE PC 1000HE), they all had the same hardware specs, and the only notable difference was battery life and keyboard/trackpad. (Well, I guess they can now more or less play higher-def video.) Sometimes odd decisions are made when rearranging or resizing the keyboard/trackpad, so pour your efforts in to gathering opinions about those things & go actually test them out in person if you can.
All that said, keyboard-related activities and the ability to use Flash aside, I find the tablet form-factor and speed much better to use. A real PC might be able to theoretically "do more," but it might all test your patience to a fault compared to the brisker, if limited, experience on a tablet. Notable tablet benefits, in my experience are:
1. Ability to view content in portrait mode. More text at a time, less scrolling.
2. What it *can* do, it does significantly faster than a netbook.
3. Less bulk.
4. Easier to use while lying down.
5. Longer battery life.
6. More focus since I can't get distracted by opening too many websites or programs at the same time.
I've got quite a lengthier list of what I hate about my iPad (G1, 16GB wi-fi), but I still prefer to use it over my netbook.
I haven't tried it personally, but I think the keyboard dock idea (a la ASUS Transformer) is the best of both world. Streamlined efficiency of a tablet with the ability to do long-form typing. The tablet-turns-into-laptop thing is better than Apple's desk-necessary keyboard dock and stays in one nice piece when transporting. They've had third-party "keyboard cases" for iPads, but they look bulky as hell and don't seem to have well-reviewed keyboards.
If you're looking for actual power in a tiny form-factor computer, there are ultra-portable notebooks like the MacBook Air, but those are usually at least triple your stated price-range.
Since a netbook performs so poorly in multimedia tasks, I think it's only really great as a casual-use, I-can-waste-time-not-efficiently-browsing-websites computer and as a word processor...but as mentioned earlier, the narrow landscape screen, combined with the relatively low resolution isn't a very friendly way to view text.
