The issue may very well be extracting the font files that you want from the backup and copying them to a new or alternate location on your Win7 machine. Without knowing the backup process that you've used I don't know that we can be of much help with that.
As far as installing the fonts, once you have them in a folder on the Win7 machine, take a look at this microsoft article and see if it helps. Microsoft Typography - Installing fonts on Windows
1. The first step is to copy the fonts from the old PC to an external drive skipping all of the fonts with a .fon file extension.
2. Back up your existing font folder in case of trouble down the road. I would also create a Restore Point within Windows (see how to do this in Windows 7 at bit.ly/restorepoint).
3. Once the fonts are copied to the external drive, disconnect the drive and connect it to your Windows 7 PC.
4. Navigate to the folder on the external drive containing the fonts and right click one or several fonts and select Install. That’s it.
Why copy to an external drive? My Vista backup which contains my Vista fonts is on my external drive (which is connected to my new Windows 7 PC. So, it's impossible to disconnect the external drive.
I expect a lot of the Vista fonts are also on my Windows 7 PC. There are too many fonts too compare. I only want to install the fonts that are 'different.' What happens if I try to install ALL the Vista fonts? Will I be asked what I want to do with duplicates?
Open the old fonts folder in your backup.
Select all, and then right click and select Install.
It will install any fonts that you don't already have installed.
When it asks if you want to reinstall fonts you already have installed, click the don't ask this again button and select either answer so it doesn't ask you over and over.