UK's Revenue and Customs has confirmed that you can bring back a copy of Vista legally from the States without paying any customs duty or VAT on it.

UK prices of Windows Vista are up to 60 per cent higher than those charged in the US - up to twice as high if you factor in Vat.

Jan Marszewski from HR Revenue and Customs confirmed you must only pay VAT " over the £145 personal allowance for everything you buy abroad" and with "CD ROMs with data or programs, there's no import duty on that."

Comparing Amazon's US and  UK Vista Home Premium prices reveals Britons will pay £210.99, whereas American's will only pay $227.99, or £116 at todays exchange rate.

If Britons want to bring in more than one copy of Vista or plan to sell their copies they must pay VAT on them, which means each copy of Windows Vista will cost £136 - still a saving of £74.99 over UK pricing.

Customers could also buy Vista on an American website and get it sent through the post for £136 excluding delivery, although PCW hasn't found US websites will to do so.

Marszewski said custom officials aren't ignorant of software importers saying "a lot of people would buy software in America because it's probably cheaper."

When we asked about customers trying to sneak in multiple copies of Vista into the country Marszewski said "our priority at the airport is prohibited goods like drugs and weapons."

But he added: "The customs officers, they can usually tell if someone has got goods in excess of £145 limit" and "we can fine them up to 100 per cent of the duty evaded" and "we may find them the amount of VAT evaded."

A London-New York return including all taxes can currently be bought for £240 inc. VAT, which means travellers would have to bring back and sell four copies of Vista to comfortably cover the cost of the trip.