[ubuntu] Cannot Reformat Drive for Dual Boot

Hi,

I have a virus on my computer so I have to reformat the drive and install a Ubuntu/Windows & dual boot. However, the problem is that when I insert my Windows 7 upgrade disk, it wants to reformat and reinstall Windows 7 only in the Windows partition. It won't recognize and reformat the Ubuntu partitions. What should I do?

I'm not very tech savvy, so detailed step by step instructions would be most appreciated.

Thanks,