Help! Can't delete a previous installation of Windows!

I had a "dual-boot" configuration of Windows XP. I had Windows XP Pro
(32-bit) installed on the boot drive and I installed Windows XP Pro x64
(64-bit) on another "drive" (it's actually a RAID 0 array).

Anyway on that RAID 0 array, there is a "C:\WINDOWS" directory, a
"C:\Documents and Settings" directory and a "C:\Program Files" directory.
I'm now using Windows Vista Ultimate x64 edition (and, yes, I realize there's
pretty severe performance hit for running 32-bit applications in the 32-bit
'emulation' mode) and would like to free up that space without reformatting
the drive. There is other data on that drive (also leftover from the
previous configuration) that I wish to keep and really have no other place to
put it temporarily so that I could just format the drive.

I am using an Administrator account and I tried to go into the "Security"
tab and take ownership of the directories, but it won't let me. Also, before
I delete "Documents and Settings" I'd like to get my data out of my old home
directory before I delete it. It also won't allow me into some of those
folders to get at my data.

Any help would be appreciated.

Thanks,
Brian
--
Brian Millikan
Computer/Software Engineer
Microsoft Control Applications (Dialog-Based) Specialist / Hardware Driver
Development / User-Level Hardware Device Interfaces