Depends on how you made the Backup Disc and what it actually is. All Volume License Product from M$ is different Install Media to the OEM or Retail Versions of the same product.
So if you mean can you use the the OEM/Retail Install Disc with the VL License Key then your answer is [b]No[/b] you can not. They involve different Product Keys that are not usable between different versions of the same product line.
Also if you load 2007 now with the Key that came with the Original you are in direct breach of the M$ License Agreement and are libel to large Fines from M$ when caught. Here the first offense is $250,000.00 with an agreement for M$ to print the companies Name, Address, as well as the Name and Address of the Companies Owners/Principles in their Enforcement Alerts which go out to the M$ Partners and is available on the M$ Web Site in your Country.
OH M$ Legal also makes you sweat it out for about 18 months so there is a substantial Legal Bill run up in the process as well before the business makes a Economic Decision to settle out of Court. The Mental Anguish is also substantial but there is no cost placed on that. ;)
Col