The advent one isn't very good.
You'd do better to go for the new MSI Wind (U120) when that is released (soon) - bigger memory, and wireless capability, at around the same price point. Battery life might suffer though.
It should be noted that I'm using a Samsung NC10, which I class as better than the new Wind only by battery life and stylishness (and keyboard, but that's more personal) - but it's around £300 now.
I'm currently using the Advent one and it's okay. The keyboard is tiny and that can be damned annoying sometimes, but it's not big problem. If you're going to do anything but browse the net and work, I'd go for a different laptop as the screen is so small it's going to get cluttered quickly and make viewing things/playing games rather annoying.
I was under the impression that the Advent Netbook was just a rebranded Wind U100.
Well technically that's kind of all it is... a re-branded, lower spec MSI Wind.
I'm VERY sceptical about the use of Netbooks. I think that to be honest, I'd rather have one if they had Vista and had a CD drive in them already. That'd be the thing that sold it to me.
As they have neither, in the meantime I think I'll stick to a laptop.
There is nothing to say, however, that you couldn't easily upgrade a netbook with 1GB RAM and a decent sized hard drive to Vista Basic though.
USB CD drives are the way forward. It's all a bit like the Macbook Air really - small, lightweight and compact but really needs all those extras to make it worthwhile (CD drive being the key thing) and to be honest it's a LOT of money for the size of it when you consider how much functionality you're missing by not having an internal CD drive.
The only other alternative is "the next best thing" - Open source software such as OpenOffice 3, (if you're into webdesign) Nvu, sound recording Audacity, movie making - well Windows MovieMaker and then if you're into graphics stuff use The GIMP.
The Linux system on some Netbooks is rather bad if you ask me.
Keypads are often too small.
THIS... is where the 12" Dell Inspiron Mini9 comes into it! Get one of those. And a USB CD drive.