*sigh*
It's getting a bit tedious seeing all these falsely described products on here, featuring completely inappropriate words and even detail descriptions so they'll catch the eye - and money - of the less technically well-informed, who are then left out of pocket with an expensive lump of plastic that falls far short of their expectations and needs.
480x320 is NOT by ANY chalk "high definition", unless maybe you've just arrived fresh from the 1930s when such words were being used to describe the BBC's Marconi-system 425 line TV service (vs the 30-ish line Baird one). By modern standards it's not even Standard Def (if you were being charitable, you could say it's half of US broadcast definition - but it's barely a third of a standard UK DVD...). It's just-about (low end - stuff such as the iPhone 3G and Samsung 8910 far outstrip it) smartphone resolution. It will NOT be any good for use with a netbook (provided you even find one that can output plain Composite Video, which is all this projector takes, rather than the VGA ports most have as their only socket) unless all you're doing is watching iPlayer videos over a lower end connection, and in which case you'd still be as well to see them on the built in screen.
By all means, have a pocket projector like this for showing off pictures or videos from a compatible digital camera, camcorder or smartphone. It's probably fine for those purposes, if a little dim and blocky. But don't be under an illusions that it's any cop for use with a computer, or that the "high definition" part of the description is anything more than a shameful, bare-faced lie. If you've laid out £280 of your hard-earned expecting such, without having the requisite knowledge to have spotted it beforehand, I'd say you have every right to shop them to trading standards for false description.
Two stars instead of one because it's at least not the abysmal 320x234 of the "PS3" projector which is also claiming to be high def and doesn't even have the common courtesy to be a pocket model.