SD memory card format

Hi,

Recently i bought a Sandisk microSDHC 4GB memory card without even checking (my mistake ) that the device i wanted to use it with, can read only up to 2 gb memory cards (FAT file system).
So i was wondering, is there any possibility (except selling the card and buying a new one) for me to format, or to make new partitions with some kind of software, or whatever.. to make this card with capacity 2gb file system FAT 16k.
I tried to format it with XP's computer management->disk management, but it only allows me to format it as FAT 64k and the volume remains 4gb which still can not be read by my phone.
I know it may sound strange that i want to make from 4gb card a 2gb card, but now it is useless for me.

So, thanks in advance for any advice