Customers making digital downloads from Microsoft can now start paying for their purchases in Bitcoins - at least, in the US. The move is another small step on the virtual currency's path to mainstream acceptance, with Microsoft becoming one of the first major tech firms to support Bitcoins.

The company will now accept Bitcoins as a means of topping up a Microsoft account, which can be used to make purchases from the Windows, Windows Phone and Xbox stores, among other things. Customers who sign into their Microsoft account and select payment options will see "Redeem Bitcoin" listed among the options. Users can then transfer the funds from a Bitcoin wallet on the same device.

It seems Microsoft is merely experimenting with, rather than fully committing to, the currency at this stage. Bitcoins cannot be used to buy physical products (such as Xbox consoles or Surface tablets) and the Bitcoin option is currently only available to customers based in the US. Microsoft is using a company called Bitpay to process the transactions.

The value of Bitcoins has fallen sharply this year. From a high of around £400 in June, a single Bitcoin is now worth around £230. At its very peak in December 2013, a Bitcoin was (briefly) worth £750. All fund transfers made in the Microsoft store will be based on the current dollar/Bitcoin exchange rate.

Perhaps wary of the potential for money laundering, Microsoft states that money added to customers' accounts using Bitcoins cannot be refunded. Bitcoins are notoriously the currency of choice for transactions involving illegal goods on the internet, largely because it's difficult for law enforcement agencies to follow the money trail.

Microsoft is probably the biggest company to date to start accepting Bitcoins. Dell started accepting Bitcoin payments earlier this year, whilst the UK-based CeX chain - which allows people to trade-in computer equipment, games and other goods - also accepts the virtual currency.