You won't be able to boot with Grub, because stage 2 of GRUB was on your Linux partition, which is now wiped.
The best bet is going to be to repair the master boot record (MBR) using your Windows tools. For example:
Hint: Read very carefully about the risks of playing with the MBR. If you damage your partition table you may not be able to recover Windows. In the future you should always have a bootable rescue floppy disk (or CD).
Hint: If you haven't backed up your critical Windows data, do that first. You can do this without booting Windows for example by booting from a live CD (Knoppix for example) and copying the essential data to whatever media you have available.