need to install OS on dimension 4100

I don't know what I'm doing wrong. I went into bios and set cd as first but only old OS comes up; no option to use boot cd.

 

Try rebooting with the disc in the drive and watch for the message "Press any key to boot from CD/DVD" That's your cue to press a key so that the machine boots from the optical drive instead of moving on to the hard drive.

 

That's the problem. I'm not getting the option to press any key; it goes straight to the old OS.

 

Try hitting F12 during the DELL splash screen and selecting CD. It might force it to use the CD.

 

Provided the old OS still works, you can run a command prompt within that and type "format c:" without the quotes and hit the Enter button (you will need to run the command prompt as Administrator if the old OS is Windows Vista or 7). It will ask to reboot to complete the task, but will clear out your hard drive once it reboots. I can't remember, but it's likely it will ask you are you sure, etc. before it asks to reboot. Then, there won't be an old OS to worry about.

Or, possibly easier, does the BIOS allow you to REMOVE the hard drive as a boot device? Obviously, you'll need to re-add it as a boot device once you've started installing the new OS, but it could at least initially prevent the old OS from loading.

 

all I get is a black screen saying invalid boot diskette

 

signing out for tonight...later