Hey John T - I think whether or not larger (4GB, 8GB and up) cards will work depends on the device.
I have an older Sony camera that will not work with any card larger than 2GB. Also an older USB "universal" card reader that won't recognize cards larger than 4GB.
Incidentally for digital photography I won't use cards larger than 8GB. I don't like "putting all my eggs in one basket" (one card) when shooting important photos. Better to spread important photos across 2 or 3 cards so if one card fails (and they do!) you don't lose it all.
Besides.....8 gig cards can be purchased CHEAP anymore.