Based on your description of its effects James,
YES. That is exactly what it is.
The site you linked points to a program called Spy Assassin and promises to 'FREES UP VALUABLE DISK SPACE'. It certainly did that... by deleting your Windows system files.
Ad-Aware 6.0 is a good program, produced by LavaSoft (
www.lavasoft.us). The site you linked likely infringes on their trademark. The site you linked has nothing to do with LavaSoft. It is a very, very common ploy of the type of spyware programs that are in fact spyware/malware themselves, to try to pass themselves off as
LavaSoft's Ad-Aware or
SpyBot - S&D.
Chances are the program download is a bunch of programs hacked together; it's unsurprising it damaged your Windows installation. I had the same thing happen once when installing a codec to view media. Though that was on a college machine so I moved along to the next one.
I reported it though so they could fix it.
Sorry you had a bad experience.
N.B for other users:
Spybot - Search & Destroy 1.3 Official Link. Good product
LavaSoft Ad-Aware 6. Official Link. Another good product.