Some N800 users have indicated that 4GB SD cards are working with OS 2007.

It might be useful to build a list of working cards by listing the following:

N800 OS 2007 Version
Card Manufacturer
Card Brand/Model
Capacity (4GB, 8GB etc.)
SD or SDHC
SDHC Class (if applicable - most likely Class 2 in most cases)
URL Link to online retailer if possible.

This might help future N800 owners with their SD card purchases!