Though the Knowledgebase says 2GB is the largest microSD card supported on the Express (in “Highest capacity memory card supported by a Sansa player”), others in this forum seem to have been able to use larger (4MB) cards with some trial or tribulation. The “MicroSD Cards note” posted in this forum back in late 2007 and signed “Sansa Mod. Team” says…
“…But the current firmware is not compatible with 6GB and 8GB. That is what is being looked into currently. Please check back periodically for updates.”
So, (1) what is in fact supported, and (2) how about that update?