How do I change my operating system to Windows 7, but save the existing Vista Business if it is needed later?

Dual boot- as suggested, partition or a new drive.

Too detailed to go into here so take a look at the links below

But remember, a full backup to a separate drive is advisable for disaster recovery! My advice is a bit-by-bit backup, but you need a drive with as much space as the drive you are backing up for this because these types of backup ignore file structure and copy each sector on the drive including free space and temp files etc. as separate bits of data, not as parts of a file.

Other backups backup data as files. You may not get everything you need to restore in the event of a catastrophic failure when partitioning.

I don't think Windows built in backup will do this, though I am not 100% sure since I have always used Acronis True Image (no affiliation beyond a very satisfied user) for this operation. There are other applications that do this, some of them free, but personally, I would be wary of risking important data with a free application. Google for more options.

Install Windows 7 to a different partition on your drive. If you don't have another partition then put in another hard drive and install Windows 7 to that. You could make another partition on your current hard drive but it's not recommended to mess around with the partition table on a disk with data on.

certain, you could improve any version of Vista to its compliant version of seven ( ex. you could improve to Win. 7 abode suitable price, professional, superb etc. from the respective version of Vista). As per section 2 of your question, i might want to recommend purely right now off asking a Microsoft tech help representative.

well the easiest way would be use the inbuilt Vista Backup and Recovery and create a complete backup of your system form the control panel

or you may have to use a better tool third party

http://www.todo-backup.com/products/home/

Make a backup before you upgrade or reinstall. If you care about your existing installation, you should already have a backup!

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