Unfortunately Vista's utility simply would NOT let me reduce the size of my C: partition anywhere near what I wanted. But I really wanted to separate my OS from my data, so I had to use Gparted. Here was my own experience using Gparted and Vista last night:
400GB HDD layout
[Front HDD]---(C: = Boot w/ Vista OS - ~391GB )---(D: = HP Recovery Partition - ~9GB)---[End HDD]
1) Stop system restore
2) Move pertinent data to another HDD in order to backup and free up space
3) Boot using UBCD4Win (Ultimate Boot CD for Windows)
4) Backup C: using DriveImage XML
5) Defrag C: using DirMS. Default option: analyze, defrag, move files to front of HDD
6) Check with regular XP Disk Defrag, look at graph and defrag C: for good measure
7) Defrag C: again with DirMS, same default settings for good measure -- Files should damn well all be moved to the front of the HDD
8) I then rebooted back to Vista and attempted to resize using the built-in utility. I had 97% free space and all files had been move to the front of the drive, yet it would only allow a 27GB reduction to the C: partition.
9) Boot into Gparted LiveCD
10) Make note of original partition layout and sector locations (start/end points)
11) Set the new drive layout to:
[Front HDD]---(C:{/dev/sda1} = Boot w/ Vista OS - ~100GB )---(E:{/dev/sda3} = New NTFS Partition ~291GB )---(D:{/dev/sda2} = HP Recovery Partition - ~9GB)---[End HDD]
*I simply resized C: and made a new primary partition for E:. No moving and nothing fancy.
12) Apply drive changes, then exit and shutdown Gparted
13) Reboot.
Vista booted, did a disk consistency check on C:, and completed booting into Vista without a hitch. No OS disc needed. All works as normal and now I've been able to move my data to a different partition and move/symlink the user and public folders.
So I hope this might help anyone looking to do the same thing.