a) look in the backup for version.txt, it will contain the version number of V5 that produced the backup.

[data]
version=5.0001a
build=5.0.2064.1
date=Fri Feb 17 09:07:43 2006
user=in2000
computer=IN2000-I9J2IGGA

The important line to look at is "build=".

b) look in the diag.txt included with the tools backup.
It will include System Start messages, that gives the build number of V5. This also provides a handy record of any upgrades that have been done, as the build number will change in the file.

(Sample from Test computer while testing new builds of V5)

...
...
03/02/2006 12:56:33 System Start 5.0.2056.6 - EnhancerTG
...
...
...
07/02/2006 16:57:48 System Start 5.0.2057.1 - EnhancerTG
...
...
...
17/02/2006 10:31:12 System Start 5.0.2064.1 - EnhancerTG