Size of new Hard Drive not recognised by Windows

Looking through the Forum I saw a question By Weid23, posted on 02/20/04: 160GB turns into 127GB???
I have exactly the same problem, the only difference being that the hard drive I fitted is a Maxtor 6Y160PO. When I installed it I followed Maxtor's instructions to the letter, using their Big Drve Enabler app. No matter, BIOS recognises the size of 160GB but Windows insists it is only 127GB. I consulted the Microsoft site and downloaded the enw Atapi driver that it told me to do. Problem. It would not install as I had installed SP2. Billie's boy's say that this driver is on SP1, and everything on SP1 is on SP2 so there is no need to install both. I looked at the contents of SP2 and they are wrong on that count, the new Atapi driver is not on it. So it looks like I'm stuck, do I uninstall SP2; install SP1 then reinstall SP2? Or is it possible to just lift that driver off the SP1 CD and install it? I've sent emails to Microsoft about this, several in fact, but they don't want to know. I would be very grateful for any ideas as to a solution.