I have been kind of out of the PC loop over that past couple years and I know in the past certain BIOS would only acknowledge a hard drive only so big, I am not sure if this is still a problem. I have a Compaq Presario PC. It has an athlon xp2800 w/VIA KM400 chipset and currently has a Seagate ATA100 120GB hard disk. I would like to put a SATA 640 GB hard disk in but not sure if one that size will work. How can I find out the max size I can use on this system?