The N800 is fine for most of what you want.

But: the screen is small. Depends on your eyes, but when you read a PDF with small fonts, you have to magnify and then the good resolution is "gone". Horizontal scrolling is not something you want.

Then there is no keyboard, and all touchpad solutions are enough to type a web address, and send a few short lines of mails, but not much more.

Of course, you can attach a BT keyboard, but then everything is getting bigger and more heavy too.

Probably there is no ideal gadget which does it all. For the best price, get the 80 Pound N770 and use it for ebooks, mp3, mails and browsing only. Later you will buy the other gadgets too ....