Can you say bios limitation. In order to access the full 200 GB, you'll either need to load a bios extender program that's usually bundled with the drive, or buy a PCI controller that loads its own extended bios, or a new motherboard. I also believe that this will only work on Windows XP with SP1 installed.
You could also partition your drive into two smaller drives, say a 120GB and a 60GB if you don't want to upgrade to XP or can't find the BIOS update...
<[color>EDIT!] I must have been sleeping when I wrote this post! And nobody caught me. If the BIOS can only see 127 GB, you cannot magically format the drive into 120 and 60. It just doesn't work that way! Without a BIOS upgrade, you are stuck with the smaller drive. Or, you could get an external drive case and plug your drive in that way. However, you will be limited in throughput speed.