About installing Win 7

hi there- I have a fairly new Toshiba laptop which has Vista. I just received the win 7 upgrade CD. What I would like to ask is if I do decide to use it and start the upgrade to win 7, and something goes wrong, will the Vista still remain on the machine and will I be able to just return to it? Guess you can tell, i'm just a little worried that if all doesnt go well, what will I do. thanx guys.

Well, it depends on the type of upgrade you are trying to do. If you are upgrading from 32-bit to a 64-bit, you will have to wipe your whole disk first.So you will not have to worry about vista becoming corrupt in this case.
If you are upgrading from 32-bit to 32-bit or from 64 to 64-bit, even if something goes wrong during the installation, you do not have to worry though. The installer will roll back the changes. However if you are worried, create a system restore point before upgrading. If anything goes wrong, do a system restore.