I could just tell you which to buy, but unless you're buying it for me, that would be silly. Buy whichever you want; they're rather different animals, and it's hard to say one is "best". I'd keep an N810 (probably an N800, actually) if I had to keep only one of my portable computers, but there are people who use them differently and would keep a netbook.

The N810 fits in your pocket, has a touchscreen, and a battery charge lasts for days when it's not doing anything (don't even need to suspend it, just let it turn the backlight off). It does have a tiny keyboard with some keys missing and a little harder to type than an Eee 701 (imho). And the N810 has a nice transflective LCD so it's quite readable in full sun, without cranking the backlight up to max and draining the battery; I'm not aware of any netbooks with this.
Nutshell: "PDA on steroids"

The netbooks don't fit in any but the largest coat pockets, have (usually tiny) touchpads, and have battery life of ~3 hours under use, ~4 hours idle (or similar), so you have to always be suspending it when not in use. They gain nicer keyboards, maybe 2 to 3 times the usable performance, and the ability to run x86 software. (And for some 9" models, 1024x600 screen over 800x480.)
Nutshell: "Baby laptop"

So they're the same price, but have completely different advantages and disadvantages; pick the one that suits your needs. If you really need the strengths of both, you're looking at at least $750.