Sounds like the data was encrypted, and if that's the case, the tech guy is basically correct. Your only other option is to do a brute force cracking of the encryption code, which could take anywhere from minutes to years.
One thing you could try, though I don't know how well it'll work, is to try installing the old drive as the boot drive for the new computer. Then stick the other one in the enclosure, and transfer the files that way if you can get into it.
You could also try something like a Knoppix boot CD, but if the filesystem is encrypted, it's not going to work any better.
In setting up my sister's new emachine desktop, I assumed I could put her old hard drive in a hard disk enclosure and transfer all her old data (pictures mostly) to her new computer's hard drive. The old computer's motherboard died.
Both computers use XP.
When I inserted the old disk in the enclosure and USB 2.0 connected it to the new machine, the old hard drive appeared as a ''padlocked'' D drive. I could not access the data. I was told by a tech support person that Windows XP does not allow accessing data on a drive removed from another computer for security reasons and that I would have to format the old drive to use it. This would defeat the purpose of buying the disk enclosure.
He said I must install the old hard drive in her new tower as a ''slave'' disk in order to access the old data? Is this true?
Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic