I installed ubuntu 11.10 but it doesn't work properly, when I choose ubuntu after I turn my pc on it just shows me a purple screen and I can never enter ubuntu.

I want to delete it and instead install the new 12.04 but every tutorial for deleting a Ubuntu dual boot says I'll need a Win 7 CD/DVD to fix the MBR. I don't have a Windows 7 DVD how can I get ubuntu uninstalled and then fix the MBR?

Do I really have to try and get a Windows 7 DVD? Does anyone know where I can get such a thing? Hoping there's a work around that doesn't require a windows 7 DVD. Thank you in advance.

Thank you in advance!