I am fixing up old computers for kids at a small church in downtown Denver. I buy them at garage sales and thrift stores. This one came from a thrift store and has Linux Mandrake 9.2 on it. Two questions: (1) I can get to the screen that asks for the local host and password. I have no idea how to get past it, and of course none of my guesses works.

I've even tried using a floppy to boot and then inserting the operating system for Windows 98 SE so I could reformat the C drive and take off the Linux program. (I've ordered a bootdisk CD to replace it.) When I get the Windows operating CD in and booted, it says "no operating system." (2) Can I reformat around the login w/ a LINUX system disk?

Just reformat the drive and install whatever OS you want on it.

try this if u want liniux os it is on the box
<a href="http://kbase.redhat.com/faq/FAQ_35_202.shtm"> faq list</a>
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or use the suggestion from second post above.

Welcome to LQ! One thing you can do is to use Knoppix, which is a Live CD. A Live CD is basically a full Linux system that runs off the CD, without writing to the hard drive.

You could boot off the Knoppix CD (make sure that your BIOS boot sequence goes to the CD before the hard drive) then run a partitioning program such as cfdisk. There are a number of threads that describe how to use Knoppix as a recovery tool, including repartitioning. Good luck with it -- J.W.