i was working only on mandrake 10 . it was working fine .. now i had some work for which i had to use only windows xp ...while installing xp i had deleted all the partitions but on rebooting it is saying missing operating system or error loading OS .....i had tried almost all teh possibilties to istall windows on my comp but failed .......plz help me out

How did you delete all your partitions?

If you say you did so, then there is nothing in the hard drive you need to backup or save. If that's the case, then its simple. Just insert your bootable xp instalation cd into your cd drive. When it prompts you to select a partition to install to, delete them all, create a new one with the size you want, format it with the filesystem you prefer (ntfs or fat32) and continue with the instalation process.

I don't see how mandrake or any linux could be interfering with the xp installation. If I misundertood you, or this does not solves the problem, could you be more specific describing your problem?

BTW, why are you going windows 100%, didn't you like linux at all?