Till recently,my computer dual booted Vista and Windows 7.After trying Windows 7 for a while,I decided to remove Vista and install Ubuntu.So I (very naively as I later found out)formatted the primary partition which had Vista and installed Kubuntu 8.10.Then I switched to Ubuntu installing GNOME.Then I realised that I could not boot into Windows 7.Its not showing up in the boot menu.After googling for a while,I found out that I might have removed the MBR on the primary partition.Is there anyway I can recover MBR and use Windows again without re-installing it?

Things I have already tried(if it is of any help)

1.Recovering from windows CD.I tried both Vista and Windows 7 DVD.Vista directly started installing it.My laptop is not recognising Windows & DVD(and a few others)

2.I've tried ms-sys.But it says:
"/dev/sda5 has an x86 boot sector,
it is an unknown boot record"
I guess windows 7 is too new for it

I would be very grateful for any help.Thanks