Overcoming the 137GB barrier on a hard drive

Our computer now is 1) OS: WinXP 2) Bios: Phoenix Technologies 6.00 PG 10/1/2003, SMBIOS Version 2.2 3) Hard drive: Maxtor ATA/100.

When we formatted this hard drive we were limited to 137GB. Maxtor's documentation says that we could have overcome this limitation if we had bought an Ultra ATA/SATA PCI card.

We are replacing this hard drive with a Western Digital Caviar SE 500GB. Based on our current scenario and circumstances, does it appear we will need to buy a PCI card for this new hard drive so we can use all 500GB's? Could the 137GB barrier problem have been with the Maxtor's software, not our computer's components?

Thanks for your help.