While surfing around look what I found on Gainward's FTP server: Nvidia/Bios/Geforce4! :D

Geforce4 MX420
Geforce4 MX440
Geforce4 MX460
Geforce4 TI4400
Geforce4 TI4600

So Hit Read more... It looks like Gainward have passworded the files but anyway here's the link:

ftp://ftp.gainward.com/Lan/Nvidia/Bios/Geforce4/