Dell Dimension 2400 and VT6421A Bios Mod

[LTFISHER]

Hi all,

I am new to this forum so first I would like to say hello and thank you in advance for any help anyone can give me.

I also hope I am posting in the correct place, I have tried to work out the best place.

Secondly I am attempting to build an HTPC using parts from old PC's. This has gone well, but I have one major stumbling block- my motherboard (from Dell Dimension 2400- Board Details) has no native SATA ports. I have a VIA RAID PCI card (VIA 3 SATA Serial ATA IDE Port PCI Card VT6421A) that I would like to boot from.

The PCI card works fine in Windows, however is not recognised in Boot. This leaves me with using IDE for my operating system, which is not ideal. From what I understand the problem lies in my BIOS, hence coming here for help.

My current BIOS is Dell AO5 (Link).
I also understand that I need to add the VT6421a ROM file to this BIOS (Link).

I have read as much as I can but do not know how to proceed. The Dell BIOS is an .exe and when I use /writeromfile in CMD the file I get cannot be opened in MMTool (which I have no previous experience of using).

So the help I ask is:

a) is what I am trying to achieve even possible?
b) Can someone help me modify this bios?
or
c) Can someone tell me how to modify this bios?

Thank you in advance for any help offered.

Regards

Luke