Important Question Concerning Ubuntu--Please Help?

Hi, first let me say thank you for reading this. I really need some tech help, I don't know what to do. Alright here is what I got going on I run Ubuntu (11.04), and Windows Vista on two separate partitions within my hard drive. The make of my computer is a Gateway T-Series Notebook. The computer came with Vista installed so I do NOT have the install/repair disk. I installed Ubuntu myself, and for some reason I don't think I did it right. I recently did a dist-upgrade and found that it messed up the system. So now I want to re-install Ubuntu because I really like it... and Windows too! I think I know how, please correct me if I am not; and I also know if I delete the partition without the Windows disc, I wont be able to boot into Vista.

I have read that you go into Computer Management in Windows, then go to the disk section. Then delete the Linux partition(s). But back to the same subject, if I do that then I can't boot into Vista. Can anybody tell me what to do, is there like an uninstaller for Ubuntu? Like is there an ISO I can burn to a flash drive to uninstall a Linux OS? Please if anybody has any knowledge on how do this please let me know, thank you in advance.

Daniel