dude.... formatin the c drive will remove the boot.ini as far as i think and u should be able to solve u r prob by
1) Insert your XP CD and boot from it.
2) You'll see some files being copied, then you'll be presented with a choice of installing or repairing an existing installation. Choose Repair.(if u dont get repair option then the rest of the steps are useless)
You'll be asked which XP installation you want to log into. Enter 1. There is usually only
one installation.
3) You'll be prompted for the Administrator password. For Home, the default password is blank, so just hit Enter. For Pro, enter the same password you did during setup for the Administrator account (this is not the same as the password for an Admin level account. It must be the Administrator account password).
4) At the C:\Windows prompt, type FIXBOOT. You'll be prompted to confirm. Do so.
5) When FIXBOOT is finished, remove the XP CD and type EXIT and the machine will reboot.
Reconfigure your computer to boot from the hard drive if necessary.
though i havent tried it on my own but its just my guess that this should work...
or else just get the xp intallation cd and just sit down with about 45-60 mins in hand and its not a great job to do a fresh new xp installation