Re: Can I add extra memory with a card
For a 640xl u need a "micro SD" type with storages starting from 1 gigabyte all the way up to 128 gigabytes. For a heavy media consumer "music downloads, movies, podcasts and apps" 64 gigabytes is more than enough. As for the class of the card well it doesn't really matter if ur gonna get anything between 4 and 10 "transfere speed differs incrementally by buying a higher class card". As for manufacturers I recommend one of the following. Kingston, SanDisk, corsair or Samsung.
My recommendations: 64 gigabytes class 10 Kingston micro SD card