I'm totally new to linux. This is a windows/linux question. I want to know if I can use one of the following linux ditros, ran from cd, to make changes to the hard drive of a windows computer.

Here's what I have:
Knoppix STD
P.H.L.A.K.
Knoppix 3.4
and Mandrake Linux

I was moving trojans from a friends computer to a safe folder. I hit 8 nasties, but the 9th turned out to be a necessary system file. The file is not deleted, I just need to move it back. Any help would be great.

Depends on file system, but with a live CD you can mount drives. If the Windows f/s is FAT then it will mount read & write no problems but, (keep in mind im a freebsd user) I think NTFS has some write issues, but maybe in Linux they dont exist. I do know however that in Linux NTFS support must be compiled into the kernel.. That could be a drawback unless you are able to setup NTFS support some other way.

mkdir /mnt/win; mount -t ntfs /dev/hda1 /mnt/win

Maybe that will work (Substitute hda1 for the Windows partition, RTM for disk naming conventions.

Hope that helps.

use knoppix

it comes with captive ntfs which lets you do what you need to do to windows. make sure you connect to the internet first though, cause it needs to download ntfs drivers from MS.