Windows 2000 does not care what size your primary partition is. If you formatted your disk using NTFS, Windows will support volumes of up to 18,446,744,073,709,551,615 clusters. That is about 64 exabytes (1 exabyte = 1,024 petabytes, 1 petabyte = 1,024 gigabytes). So, 170 GB is really not much. In any case, I have a 180 GB disk, and it shows up as 171.6 GB. No problems.
I don't know where your problem is though. Sorry.