PC will not bootup after power outage.

After a power outage, my PC (WIndows XP) will not completely bootup and keeps returning to DOS prompting me to select either Safe Mode, Return to Normal Mode, etc. I tried all choices avail. but to no avail. I was told by a friend to insert my Windows XP CD and to try booting from the CD, but since it is an upgrade CD it prompts me to insert the original OS CD which was Win98. I can’t find that CD; is there another way to reboot?