How to install a clean bootloader to MBR?


I have been trying to set up a W7/Ubuntu dual boot with a great deal of effort. I resized the W7 partition on my Lenovo x120e, then installed (after several tries) Ubuntu 11.04. After rebooting, I was confronted with a grub prompt. Using grub commands (e.g. root (hd0,0)), I was able to boot into W7. I set up Easy BCD to put both Ubuntu and W7 in the boot menu, with Ubuntu listed first as the default. I had to reinstall Ubuntu, then grub for Ubuntu again, etc. (don't ask), but now I have a system that presents the Ubuntu grub menu, with TWO Windows 7 disks listed (sda1, sda2) as options. Booting the first W7 choice results in the Windows boot manager being flashed on the screen for a fraction of a second, then back to the Ubuntu boot manager. I can see Ubuntu and W7 listed on the Windows Boot Manager screen, but I don't have time to make a choice let alone hit any buttons.

If I pick the second W7 disk on the Ubuntu Boot Manager screen, the Windows Boot Manager comes up, and I select Windows. W7 starts to boot up , then freezes when the windows icon shows up. I then get a message about a missing MBR-helper.

If I pick the Ubuntu installation at the Ubuntu Boot Manager, btw, it boots fine into Ubuntu.

What can I do to repair my Window boot loader so I may have access to both Ubuntu and W7? Thanks.