You can use a free program like
GParted or
QtParted (both frontends to libparted), or a commercial program like
Partition Magic or
Disk Director to resize and create the appropriate partitions. I'm pretty sure you can't have the disk mounted when doing this, so a LiveCD like
knoppix (which includes QtParted) would be a good idea. Once you have created the new partition for
/home, copy all the files in
/home over to the new partition, then add a line for that partition to your
/etc/fstab, using the existing entries as a template.