One of the great things about storage cards is the ability to transfer from one device to another. Unfortunately, once you add one to your Windows Phone 7 handset, that luxury is no longer yours.According to TechRadar, it's not just a case of not being able to use the card elsewhere - you can't even replace the card with a different one. Indeed, Microsoft's help and support site says: 'You should not remove the SD card in your phone or add a new one because your Windows Phone 7 device might not work properly. Existing data on the phone will be lost, and the SD card in your phone can't be used in other Windows Phones, PCs, or other devices.'Why is this? Over to Microsoft: 'To help ensure a great user experience, Microsoft has performed exhaustive testing to determine which SD cards perform well with Windows Phone 7 devices. Microsoft has worked closely with OEMs and MOs to ensure that they only add these cards to Windows Phone 7 devices.'If you do remove the card, then 'all phone functionality is disabled except for the ability to make emergency calls. The phone will function normally again only if you reinsert the original SD card and then start the phone.'But there is a upside to this right now - currently there are no phones in the UK which have SD storage capacity. However, they are likely to head to the UK soon. With that in mind, you've been warned, should you like to swap cards around between phone and PC.