If you had Windows and Linux running on your system and just formatted the Linux partition you probably can’t load Windows anymore because the boot loader can’t load its configuration.
To solve this problem boot your pc using a Linux installation cd-rom that uses grub as the boot loader (typically right after the system boots it will show the boot loader menu) – recent distributions have fancy boot loaders with graphical interfaces, avoid those for this.
Use Backtrack Linux for example.
On the grub meny type ‘c’ for a command line and then type the following commands:
grub> rootnoverify (hd0,0) grub> chainloader+1 grub> boot
You should be booting into Windows XP.
Now to restore your Windows MBR download MbrFix from www.sysint.no and unzip it to a local folder.
Open the command prompt and enter the following command:
Mbrfix.exe /drive 0 fixmbr
Press Y and you should have your MBR fixed. You can reboot your system.