Microsoft’s newly unveiled Windows Phone 7 handsets come with the ability to expand storage with the help of external microSD chips. However, while this can help you add more content to the phone, it is not technically swappable. That is, users cannot simply cannot take out the microSD card and replace it with another card. This is because of a new system that integrates the external storage with the main memory while processing data. Microsoft explains,
“Windows Phone uses a special high–performance SD card that works differently than SD cards in other devices. When your phone is built and first set up, its internal storage and SD card are combined and recognized as one storage system. You should not remove the SD card in your phone or replace it with a new one because your Windows Phone won’t work properly. Existing data on the phone may be lost, and that SD card can’t be used in other devices or Windows Phones.”
What this means is that you can swap microSD cards, but only after a hard-reset which will basically wipe out all data on your phone. Not something that will thrill you, but then this is also something that should not affect most users since not everyone needs more than the basic 8GB or 16GB of content.