How to boot into Windows after installing grub?

I did this very clever decision to set windows 7 bootloader to ubuntu. Now I cannot boot back to windows.
If I try to boot via grub it shows the windows bootloader for half a second and goes back to grub. Also the safemode of windows ceased to work, so I cannot go back and change the settings. I am totally screwed here and would not want to install the OS (both of them) again...