I don’t know about other rescue discs. You should be able to create a Windows rescue boot disk from any Windows installation on another computer installed with the same version. If you’re thinking of dual-boot systems, bear this in mind in future! But of course hindsight is always 20/20. If you are able to find a rescue disk, you may find the guide (for Windows 7, but it’s similar) for recovery in How to Fix Windows 7 When It Fails to Boot .
In the meantime, if you’re going to upgrade to Windows 8 soon anyway, you’re best bet is probably keeping GRUB until you do. And while you’ve still got Vista, you also may want to keep the installation of a sensible operating system on your hard drive :).