INACCESSIBLE_BOOT_DEVICE with Win2000 on a Gigabyte GA-7VAXP Mobo.

[Reverend]

What chipset does your old motherboard have?
I see your new Gigabyte board uses the newer KT400 chipset.
If you replace a mobo with one that uses a different chipset this can cause problems.

There are several solutions,which all refer to problems that arise when changing motherboards.You can find them here

If none of the above fix it,use the recovery console and run either Fixboot,or Fixmbr. Instructions here

Good luck