I haven't tried this on a 2 gig MicroSD card, but I did do it on a 2 gig MiniSD card I have, so I know it works. I make no representations regarding whether this will work on a 2gb MicroSD drive, but it should. Use at your own risk.
Go to
TeraByte Unlimited - Boot Manager, Partition Manager, Drive Image, Disk Copy and Drive Wipe Utilities and DL BootIt NG. You can create a boot disk or cd that you can use (in maintenance mode without installing BootIt NG to your hard drive -- I don't recommend installing to HD, as it messes with your MBR). In maintenance mode, be sure to go into settings in BootIT NG and check USB 2.0. BootIt NG can then address USB 2.0 Devices (if your computer has USB 2.0 in the Bios) and you can use it to zap the MicroSD card and create a 1 gig partition and a 1 gig empty space. That should tide you over until RIM comes out with a firmware update that allows addressing the entire 2gb.
Once RIM comes out with updated firmware, you can offload everything from the MicroSD drive to your computer, then use BootIT NG to nuke the partitions. You can then use Computer Management\Disk Management in XP to create a 2 gb FAT partition for your 8100 to address.
I was able to do all of the above except stick the MiniSD in my 8100 and use it (for obvious reasons).