How do change my MBR on my dual boot XP Netbook?

I have an Advent 4213 Netbook which has Ubuntu installed. I know how to remove the partitions but I need to change the MBR to get rid of the GRUB boot loader. My netbook does not have a CD drive so I cannot boot from a Windows/recovery CD. Is there a way I can do this from a bootable USB drive or from within Windows XP?