A combined HSDPA/3G/GPRS modem in a USB key

Wifi hotspots are all very well when you're in one, but they're a bit like policemen: you can never find one when you really need one.

Fortunately 'mobile broadband' is taking off in a big way, so now there's no need to be in a hotspot to have mobile net access on your laptop.

The first datacards operated on GPRS. I had one on Orange for about a fortnight before giving up on it. It was slower than dial-up (48kbps vs 56kbps) and coverage was hopelessly patchy in those early days.

Then along came 3G cards, operating at 384kbps - about the same speed as the very first generation of home broadband. Coverage was still flakey, so at that stage I stuck to wifi hotspots.

Now we have the latest incarnation: HSDPA. HSDPA is typically around 1Mbit - about the same as a basic home broadband connection today - and can be up to 5Mbit.

HSDPA coverage is a bit like a trip down memory lane to the very early days of mobile phones: coverage is limited to major cities, airports and motorways. But it's growing rapidly, and fallback is to 3G (and then GPRS when needed).

I initially tried a '3' dongle, which was a disaster from start to finish: both hardware and customer service. Or disservice, I should say.

I then switched to Vodafone. The Vodafone USB key is not only smaller and more convenient, it's also completely self-contained for Windows users: all the drivers are on the key itself. Just insert the SIM, plug it in and it installs itself - so you can lend it to a friend or client when needed.

In use, you get a coloured LED to let you know what sort of connection you've got:

Green: GPRS
Dark blue: 3G
Light blue: HSDPA

So far, I have to say it spends more time in 3G mode than HSDPA, but that's fine for email, which is my main need when on the move, and it Just Works.

Within the UK, £15/month gets you 3Gb. I'm told Vodafone is understanding when you exceed this, initially just warning you and then bumping you up to the £25/month 5Gb service (er, I mean, 'unlimited').

Overseas, you pay per Mb, so it is usually cheaper to use hotel wifi services, but it's still good to have an alternative to fall back on when needed.