Don't worry. The final "i" was only optional. Perhaps it was just there to specify the onboard Intel 740 VGA. But there's only one model of any M750 out there.
The latest BIOS update is of 3/2000, available from my site:
http://go.to/ajz
BTW, it's one of PCCHIPS' better motherboards
Oh, and an AMI BIOS of that date "should" support very large HDDs.