You have a choice of at least 2 ways.
1. Get a copy of PartitionMagic, which can create, delete, and format
partitions and can also move, shrink, and/or expand them
nondestructively. PartitionMagic is available online (powerquest.com) or
at any decent computer store. If you've got a working W2k in that 2GB
partition, you may want to expand the partition to 4-5GB. I recommend
you create at least one more partition in the remaining unallocated
space, for data and software you don't want to lose if you have to
format C: someday for some reason. It's not a very good idea to put all
your eggs in one b.
2. Reinstall your OS from the beginning. This time, tell the install
process to delete the 2GB space, create an xGB partition, format it, and
install to it.