Not able install windows XP

I have a compaq presario desktop 5000 bought like 5 yrs back came with 98 preinstalled.

I had installed 2000 server , proffessional and XPP on the same drive.
Recently OS crashed.
Tried fdisk and format but was unable to format the hard disk completely.
When I boot the system it still takes me to 2000 which does not take me any further.

When I use the recovery CD it atleast takes me to dos prompt. Its strange , but even after formatting the hard disk it shows space of 1GB whereas the hard-disk size is 15 GB
Still I tried to run setup of XP/2000 over dos prompt it says it needs windows to start the installation.

I have windows XPP and 2000 advanced server CD’s .
Dont know how to install OS.