MBR bootloader issue

I was trying to install Ubuntu to an external hard drive and the installer attempted to install GRUB to the MBR of the internal drive. For some reason, that didn't quite work and now I can't boot into Windows. Whenever I try to boot into anything that requires BIOS emulation (either Windows or Linux), I just get a blinking cursor. Booting from the Windows 7 DVD and choosing to repair the startup didn't fix the issue. Does anyone know any way to fix this, preferably without having to erase everything?

Here's the output from rEFIt's Partition Inspector, if that helps:

* Report for internal hard disk *

Current GPT partition table:
# Start LBA End LBA Type
1 40 409639 EFI System (FAT)
2 409640 318914599 Mac OS X HFS+
3 319176744 488397127 Basic Data

Current MBR partition table:
# A Start LBA End LBA Type
1 1 409639 ee EFI Protective
2 409640 318914599 af Mac OS X HFS+
3 * 319176744 488397127 07 NTFS/HPFS

MBR contents:
Boot Code: GRUB

Partition at LBA 40:
Boot Code: None (Non-system disk message)
File System: FAT32
Listed in GPT as partition 1, type EFI System (FAT)

Partition at LBA 409640:
Boot Code: None
File System: HFS Extended (HFS+)
Listed in GPT as partition 2, type Mac OS X HFS+
Listed in MBR as partition 2, type af Mac OS X HFS+

Partition at LBA 319176744:
Boot Code: Windows BOOTMGR (Vista)
File System: NTFS
Listed in GPT as partition 3, type Basic Data
Listed in MBR as partition 3, type 07 NTFS/HPFS, active