hyddyn,
Yes it will, the only limitation is that the windows driver must be loaded for the device to be tested. For example video drivers will not load in PE so the video card will not be tested fully, just basic VGA functions. The same will hold true for any other devices that PE will not allow drivers to load. PE was designed as a pre installation environment and not a diagnostics environment. We do however have many clients using it, you just need to be aware there are limitations.
If a lightweight environment is desired, take a look at the DOS environment. It is used on the manufacturing lines of many of the top OEM's. It is has a feature rich command line options that allow it to be configured to perform to your specifications.
-Fred