It's a sustained transfer rate though. Normally, you wouldn't be constantly
getting full transfer rate. You'd be getting 5 megs here, 2 megs there etc.
ATA33 is fine. Seriously, I have a drive I put in this machine when moving
large amounts of data to another machine, and it's connected via an ATA33
cable. It's plenty fast.
It depends on the jobs... for many people the hard drive is one of the
primary bottlenecks. After considering the seek time, using the higher
ATA mode will still be likely to cut the transfer time in half... so what
if it's only 5 MB? Until that 5MB is transferred the whole system may be
waiting.
PCI IDE cards are always a waste, since they chew up both CPU and PCI
bandwidth.
PCI IDE cards use busmastering, they do not require ANY CPU time... it's
just the opposite, you're wasting the CPU's performance every time it has
to wait on data from an ATA33 IDE interface.
It is true that a PCI IDE card's consumption of PCI bus bandwidth is an
issue to consider on modern systems, but on the OP's aged motherboard, his
IDE controller, while in the southbridge, is still linked logically as a
PCI device, so it's "on" the PCI bus and it's lower ATA33 speed just makes
matters worse in another regard, moreso than a PCI ATA133 card would.