laptop So Sony has a new laptop out - well actually, it's a netbook - and it weighs only 780g. It's also really, really small in spite of its 11in screen: just 278mm wide, 185mm deep and 14mm thick.

Unfortunately, it's also the most expensive netbook you'll find. Having grabbed the attention of the mass media by playing the headline weight card, Sony can now rightfully boast that it has the World's Lightest Notebook. Hmm, and?

Sony X11 netbook

Well, there's something to be said for light, as anyone who's lugged a 4kg monster around on their shoulder will agree. Being both light and small can be considered A Good Thing - providing that the mass/dimension shrinkage doesn't come at the cost of comfort, or performance.

Ay, there's the rub. Our collective cool gadget antennae started twitching when the Sony VAIO P-Series was announced at the end of last year. And the same antennae sagged bunny-like when we saw how unbreathably slow it was.

Not only did Sony saddle it with the slowest processor it could find, a 1.3GHz Intel Atom, but it then strangled the poor beast at birth by loading it down with Windows Vista Home Premium. Ouch.

The various Sony P11 and P19 models were priced between £849 and £1369 back in January. You can now find a P19 for less than £690. Although anything more than 200 quid for one of these Psion lookalikes is still overcharging, for what is a pocketable computer slower than the cheapest netbook - even if it does fit into a baggy back pocket.

So Sony is back into the small and expensive netbook space with the snappily named VAIO VPC-X11S1E/B. Or you may prefer the Sony VAIO VPC-X11Z1E/X, if the former's £1,300 entry price just seems too cheap and you want to trade up to the £1800 flagship.

What's the difference between models? Both get 2GB of slow DDR2 RAM. Both feature an Intel GMA 500 graphics chip, which will crumple if you wave a Windows game near it. And both include 802.11n wireless with an option on 3G wireless too. The difference between models is 128GB vs 256GB SSD, and 1.86GHz or 2GHz processor.

Sony X11 netbook

The Sony VAIO VPC-X11S1E/B netbook

At the Sony launch yesterday, I had a hands-on play with one of these X11s. Yes, it's incredibly light. And it feels rather fragile, as if it will snap if you so much as look at it too hard. The real disappointment though was how slow it felt in use.

It may have a new Intel Atom that goes up to 2GHz inside, yet moving windows around the desktop left a ghost trail of frames behind. Opaque window frames too, because someone had tried the same trick as was pulled with the first P-Series press samples - switching off Windows Aero in an attempt to speed up the user interface.

Switching Windows Aero ‘on' simply treacled it to the point I'd be tempted to lift its sublime featherlight sub-800g frame high into the air... and hurl it out an open window in frustration.

So is Sony lining itself up for another overpriced fail with the X-Series? Time will tell, and we look forward to testing a production model in the lab soon.