Got a note from Gigabyte tech support saying that their old GA-6BXE
motherboard does not support hard drives larger than 75 GB because
of a limitation in the 440 BX chipset which it uses.

Is this actually true? I have not come across a 75 GB limit.

No, it isn't true and Gigabyte knows this!

I have a Gigabyte GA6BXD running, also with 440BX chipset and it runs
with my Samsung SP1614N (160GB) very well.

But You should ensure, that Your OS can handle such drives. For
Windows XP I gues You have to install the ServicePack 1. Don't know
with W2K.

I'm pretty sure, that Your Mobo will support the drive, too, also
there is only 136GB written in the bios like it is done in my bios,
too.

BUT: The BX-chipset isn't very fast for current drives. UDMA33 is much
to less to let modern drives perform well.

Moritz