Anyone who has shopped at the discount store TK Maxx and paid with a card should be worried.

Their computer systems in Watford were broken into by hackers, and details of millions of customers were stolen.

The hackers were at work between July 2005 and the end of last year, and got information on customers from the UK, US and Ireland.

And the details have already been used to defraud people.

Although we all worry about whether websites we use are secure, in this case the problem didn't just affect customers buying online.

Anyone who paid by card in a shop since December 2002 had their details stored, at least 45 million cards.

Fortunately most of us in the UK have had new cards in the last year, and our chip and pin cards have different numbers so the old cards are no longer valid.

But there is a real danger that TK Maxx shoppers will be the victims of card fraud. So far banks have not said that they will issue new cards with new numbers to TK Maxx customers.

It would seem like a sensible thing to do. The way that card details were stolen from TK Maxx highlights one of the big problems with computer databases.

They often hold so much valuable information that they are a very tempting target for thieves.

Sometimes they can be accessed over the internet, which makes it easier for hackers to break in.

But often it is people working inside companies who steal customer information, and that is very hard to control.

The real lesson we can learn from the current scare is that we all need to keep a close eye on our bank accounts and credit cards.

Even if we shop at big retailers and never use our cards online, we can still be exposed to fraud.

This means keeping a close eye on monthly statements and asking your bank about anything unusual.

Under new rules any frauds are now reported directly to your bank or credit card company and they then tell the police.

This should make life simpler. And of course, if it isn't your fault then you will get a refund.

More information: http://news.bbc.co.uk/1/hi/business/6509993.stm

My sister Julie has bought a new computer, and it came with Vista, the latest version of Microsoft Windows which was launched earlier this year.

When I was visiting her last week I got to see just how the new operating system, which Microsoft has spent billions of pounds creating and promoting, is really being used.

But first I had to fix it, because Julie's old printer wouldn't work with the shiny new computer.

It would print stuff, but refused to scan or copy documents, even though it used to. She had even gone to the trouble of going online to find the latest version of the printer driver, the small program that controls how it works.

After about ten minutes of fiddling around I did the obvious thing. I unplugged the printer, uninstalled it, rebooted the computer and plugged it back in.

The computer recognised the 'new' printer, and I told it that it was okay to install it. And it worked this time around.

It may well be that Julie had simply clicked the wrong button first time around, but the problem was that she had no way of figuring out what was actually going on.

Although she knew how to use her old computer, Vista is so different that she was starting from scratch.

She is not alone. Millions of new computers are being sold with Vista on, and lots of people who have only just got used to the old way of working are expected to cope with a whole new approach.

If Julie, who is quite experienced with computers, finds it tricky, then I can't imagine how my dad, in his seventies and really unsure of what he is doing will manage.