DriverPacks BASE does ID your OS on the location screen... right under where the path is displayed...
validating an install disc is not a worth while task, mostly because there are so many different sources.
Three main types: Home, Professional, Media Center.
Four Service pack levels
and several distributions; Retail, MSDN, Volume License, Corporate, and an untold number of OEM provider versions like Dell, Sony, Toshiba, Compaq, HP, ETC...
Resulting in an almost infinite number of "valid" possabilities...
IE Just consider that the 3 main types to the exponent of the four SP levels (0~3) alone would be Eighty One possabilites 3^4 = 81
take 27 to the exponent of at least 4 main distributions 81^4 = 43,046,721 ... forty three million possabilities, AT LEAST!
Take 43 million and multiply that times the number of files on an XP install disk and the result is an insane number... 
- Let us know if you need help with that project, We will be glad to supply testers to see if your application works or not.
If there is a Hologram on the disc, then it's a good one. that works every time, and is a lot easier. 
Or if you download it directly from MSDN, then it is a good one .
not to put to fine of a point on it but if you have to wonder whether or not your source is valid, then it is not valid 
.
Good thinking though... It is a nice idea, it is just not something that could be implemented in a reasonable amount of time.
If I understood you correctly... Then we are glad you solved your issue
