Help!! with Dell Optiplex GX280

Ok, I know I'm old and dummer than a rock, but this thing is driving me nuts. I purchaced the computer from where I work for a song when they were in the process of upgrading their systems. I bought some more RAM and a new hard-drive. The problem is when I try to boot up to do the clean install of windows Xp on the new hard drive I get the message " No bootable disc" or something similar. I've looked every where I can think of to get information. Got any ideas group?

 

As the pc begins to boot and you see the Dell logo pres the f12 key a couple of times and you should get a menu list that will include a boot from cd. Highlight that choice, and be prepared to hit another key when prompted. Be sure to have the Windows cd in the drive when you start.

 

Thanks for the input.... You're not going to believe this one. I had tried both suggestions prior to the posting. For some reason when I went back and tried them again they worked...!!!!! DUH!!! You've got me. Thanks for the help though. This is a great web site.