The ST94811A is a standard IDE drive - you should be able to replace it with any other IDE (also called "ATA") laptop drive. The only thing to watch out for is that if you use a drive larger than about 137GB you won't be able to access the whole thing unless you have at least Service Pack 1 of XP or later.
Thank You for the information. That laptop has been lying there for more than eight months. I'll try to find the hard drive that will best fit the space. Thank you again and more power to you !