Yes and no. They can identify system hardware and their drivers, chipsets & their revisions, bios versions, etc.
I have found it necessary to ID these things since Win 7 does not get every driver or version.
I recently installed Win 7 on a second drive, and although the W7 compatibility tests showed my video and sound cards and drrivers to be "GO", they were not found or installed by W7. I will use the Belarc & Piriform test results to ID & hopefully allow me to locate the exact drivers.