Older computer has compatibilty problem, often they don't recognized hard drives older larger than 30G. You can go to the computer manufacturer or motherboard maker's website to download an updated bios for your motherboard to fix this problem. Or, you can go to the IBM website to download a partitioning software, Disk Manager. The Disk Manager will insert a driver ibto your computer to make it recognizedas a 40G hard drive.
The fastest computer is not necessary a good running computer.