Windows Folders locked

I guess Mac OS X Leopard is treating all the folders I have on my USB hard drive from Windows XP (My Music, My Pictures, My...etc) as locked system directories. Since it did not create them, it seems that I cannot use the "Repair Privileges Utility" to reset permissions back to normal. I want to copy more files into "My Pictures" on my USB hard drive (which acts as a scratch drive for my pictures), rename it Pictures. This volume is a USB hard drive that contains a backup of my roommate's hard drive, thus it would be difficult and time-consuming to copy the files to a new folder on the Mac volume, reformat the USB disk and copy back the files (and I do not know if my roommate would be able to see the new volume on his Windows box). how do I unlock these folders? thank you.

What file system is the USB drive formatted in? If it's NTFS, then OS X is incapable of writing to an NTFS-formatted drive. It can read it, but not write to it.

If this is the case, then I recommend installing a couple free packages for OS X that will enable it to write to NTFS-drives. First you need to install MacFUSE:
http://code.google.com/p/macfuse/

After installing that, reboot, then install NTFS-3G:
http://www.ntfs-3g.org/

This should work out for ya. Let us know one way or the other.

USB drive now not mounting

I followed your instructions and now I get this error message when I plug in (ie mount) the USB hard drive:

NTFS-#G could not mount /dev/disk1s1 at /Volumes/Untitled because the following error occurred:

$LogFile indicates unclean shutdown (0, 0)
Failed to mount '/dev/disk1s1': Operation not supported
Mount is denied because NTFS is marked to be in use. Choose one action:

Choice 1: If you have Windows.... (omitted because it is irrelevant)

Choice 2: If you don't have Windows then you can use the 'force' option for your own responsibilty. For example type on the command line:

mount -t ntfs-3g /dev/disk1s1 /Volumes/Untitled -o force

Or add the option to the relevant row in the /etc/fstab file:

/dev/disk1s1 /Volumes/Untitled ntfs-3g defaults,force 0 0

I would copy all the files onto another computer if possible and than format the Flash drive using disk utility and than copy them back on and see if it works.

Not a flash drive

This is an 160GB External Drive. I don't know if this makes a difference. Also, please tell me how to uninstall NTFS-3g; I need to at least have access to this drive (before I installed NTFS-3g I had access to this drive--and some of the files could be modified--just not the Windows "My ..." directories) Thank you.

If the drive is formatted in NTFS, then you couldn't have modified files before installing NTFS-3G. OS X, without any 3rd-party help, CANNOT write to NTFS volumes, only read. I have NTFS-3G on my system and I can read/write/modify/do-as-I-please to anything on my Windows XP partition, so something else is wrong with your set up.

You did install MacFUSE first, didn't you?