The reason for the 147 vs 160 difference is due to fact that hard drive manufacturers define a gigabyte as 1,000,000,000 bytes, whereas at the pc software level a gigabyte is defined as 2**30 or 1,073,741,824 bytes. So, what a hard drive manufacturer says is a 160gb drive is a drive with 160,000,000,000 bytes in capacity, but to software like PM it is actually 160,000,000,000 / 1,073,741,824 = 149.11gb (roughly what you are seeing in PM).

So are you saying now that if you run the Dos-based PM that it shows you there are currently no partitions defined? If not, what does it show as defined?