If I am only upgrading my Windows partition from Vista to 7 will it erase my entire drive and I will have to reinstall Ubuntu as it would if I fresh installed it?
I currently have 12.04 and Vista installed on separate partitions on the same hard drive. If it merely eliminates Grub I know how to reinstall that.
When you are installing 7, you can select the partitions for the system. If you do not erase/format the Ubuntu partition, then everything should be fine.
One thing could be a problem: Windows will override the bootloader, so grub will be gone if it's on the same partition. If you start your system after the Win 7 installation, probably Windows 7 will boot without any other options -> so you cannot start your Ubuntu. But that's fine, you just have to reinstall grub. The easiest way should be using boot-repair
