Can someone help me with dual-booting Windows 7 and Vista? -

I have already partitioned 20gbs for windows 7 and downloaded it. I burned it to a DVD and I start it, go to advanced instillation, and I choose to install to drive W (my partitioned drive). I did it, but after it copies and extracts all the files it has to restart. It does this, but then I get some kind of error message before windows starts that the drive is messed up. If i press enter twice I can get past this, then I get to the dual-boot screen and I have two options, Windows Setup (or something like that) and Windows Vista Home Premium. I click Windows Vista Home Premium and it tells me that the instillation of the new operating system did not work and it is reverting back to the old one. My computer still works, but it does not start the install back up, so I have to start over. I have tried just starting up the instillation again and it does the same exact thing as the first time. Help! Thank you.

Is this on the same hard drive? Just for the record, I d never put a beta on the same drive as another OS that you need. And what seems to be happening is that your Windows 7 is not installing properly and then it seems to be messing up the MBR of the drive. This is when Vista returns it to normal by changing it back to the default MBR when Vista was installed.