[CentOS] disk partitioning - I'm missing something simple, I think

Hi all,

Excuse the question as I'm sure those more experienced will find it simple.

I've a CentOS5.1 box with six physical drives, two of which are used for 
nightly rsync
 backups.  Contents of /etc/mtab, /etc/fstab, df and a brief narrative 
follow:

======================================================
# cat ./fstab
/dev/VolGroup00/LogVol00 /                       ext3    defaults        1 1
LABEL=/home             /home                   ext3    defaults        1 2
LABEL=/home/adminusers         /home/adminusers               ext3    
defaults        1 2
LABEL=/boot             /boot                   ext3    defaults        1 2
tmpfs                   /dev/shm                tmpfs   defaults        0 0
devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
sysfs                   /sys                    sysfs   defaults        0 0
proc                    /proc                   proc    defaults        0 0
/dev/VolGroup00/LogVol01 swap                    swap    defaults        0 0
======================================================
# cat ./mtab
/dev/mapper/VolGroup00-LogVol00 / ext3 rw 0 0
proc /proc proc rw 0 0
sysfs /sys sysfs rw 0 0
devpts /dev/pts devpts rw,gid=5,mode=620 0 0
/dev/sdc1 /home ext3 rw 0 0
/dev/sdd1 /home/adminusers ext3 rw 0 0
/dev/sda1 /boot ext3 rw 0 0
tmpfs /dev/shm tmpfs rw 0 0
none /proc/sys/fs/binfmt_misc binfmt_misc rw 0 0
sunrpc /var/lib/nfs/rpc_pipefs rpc_pipefs rw 0 0
======================================================
# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
                      131G  4.7G  120G   4% /
/dev/sdc1             271G  147G  111G  58% /home
/dev/sdd1             271G  3.9G  253G   2% /home/adminusers
/dev/sda1              99M   20M   74M  22% /boot
tmpfs                 442M     0  442M   0% /dev/shm
======================================================

Each night, in addition to our tape backup paradigm, an rsync script is 
run which mounts /dev/sdb1 on /mnt/sysinfo and copies system data from 
sda1 there.  /dev/sdb1 is a 146GB drive.  The script then mounts 
/dev/sde1 on /mnt/userdata for a copy of /home and /home/adminusers.  
/dev/sde1 is a wholly underutilized 300G drive.

I'd like to move the contents of /home/adminusers from /dev/sdd1 to 
/dev/sdc1 and use that underutilized drive elsewhere.  What's the least 
invasive way of doing this given the hardware and partitioning on my system?

Thanks in advance,
-Ray