HD recognition problem

Installed 40GB Western Digital and updated BIOS to handle larger drive. I did not install WD’s Data Lifeguard Tools which includes EZ-BIOS. I was advised not to because of the BIOS update would take care of the recognition. CMOS recognize full 40GB. Windows only recognized 37.2 GB. I have searched Windows Knowledge Base, TechPro Guild Q and A, and Mueller’s Upgrading and Repairing PCs (11 Ed). I have found no answer concerning this specific problem. Help! Certain programs don’t run properly because of this situation. Thanks in advance.