For future searchers:
I used Gparted Live CD to reduce my c: partition to 35gb. On the first reboot after the resize I had to let Windows fix itself (it was confused by the change in its system partition) but it finally worked it out and finished booting. I found that some people have had trouble with Windows booting after the resize (like they say it won't at all), even though mine was fine. See here:http://www.howtogeek.com/howto/windo...sta-partition/
Editing the partitions did permanently break the ability to hit f8 during POST to go into Dell Image Restore, (it overwrites/replaces the Dell OEM MBR) but here's a work-around that allows you to still use Dell Image Restore if you need to.
I found out that to access the Dell Image Restore I have to:
-While still in Windows, look at the folders on the root of the Recovery partition. In a step below, you'll need to recognize this drive by the folders you see now.
-boot to OEM Vista CD by inserting it and hitting f12 during POST
-allow several minutes for files to load
-Select language, etc. Next
-Select Repair Your Computer
-After it scans, hit Next
-On menu of options, select bottom option "Command Prompt"
-In the command window, determine which drive (probably d: or e: ) is the repair partition by looking at the contents (remember the first step above)
-Using the drive letter of the recovery partition, set path to this: e:\windows;e:\windows\system32
-At the Recovery partition's drive letter prompt, type: cd tools
Now you're into Dell's Image Restore and it will make your c: drive exactly like it was the day the computer was unboxed. Make sure to backup any data you want that is on c: before running the Image Restore because it will be gone.