If you have a blank cd-r and can burn a disk on another machine go for the repair cd image for 7 at the Neosmart link. That will have what you need.
The other option would be seeing the disk image written to a usb flash drive made bootable. Neosmart provides the repair tools for both Vista and 7 originally intended for those with laptops/desktops that came without any recovery media.
You still need to be able to boot live with a disk(or flash drive) for the repair tools. If you are unable to boot into safe mode even you know the boot sector has to be repaired.
As far as your important files there are different options for backing those up even without Windows loading. The first is simply installing the drive on another machine internally or easier use an external usb enclosure for seeing that backed up to the replacement external HD once you have that.
The other OSs can also provide a non Windows method when running a live session for access to the C volume while booting from a live cd or dvd or even a live flash drive. Using the "Other OS" For a USB Rescue Device?
These are some of the things you would look at prior to the last final option of seeing a full recovery meaning the C volume is wiped clean for the fresh copy of Windows.
First finding a way to get you booted live in order to make repair efforts first however is what to focus on. The methods for boot repair when tried will likely see fast results and get you running again. A basic quick fix rather then trashing everything when a full recovery after a drive wipe seems a bit unnecessary.