Hi.Altiris only reports on the data in the BIOS via (custom) inventory.
To actually change the information that is recorded in the BIOS, you would need to use the manufacturers utilities.
On Dell machines, this used to be ASSET.COM. In newer Dell & HP machines, you can update this manually in the BIOS.
What hardware are you using? Try and read the manuals for the PC.
Hope this helps.