SATA Drive Performance Problems

I have recently upgraded to a SATA HD and I've noticed that in one
situation, it's a lot slower than my IDE drive was.

It's when I'm burning multiple DVD's (using Nero) at the same time from
files on the HD. With my IDE drive, there wasn't any noticeable
difference in duration between burning 2 DVD's simulatenously or just 1
DVD, but with the SATA drive it seems to take twice as long when I'm
doing 2 DVD's at the same time.

My DVD writers are on separate IDE buses so there's no conflict between
them.

Any ideas why the difference in duration with the SATA drive?

I have recently upgraded to a SATA HD and I've noticed that in one
situation, it's a lot slower than my IDE drive was.

It's when I'm burning multiple DVD's (using Nero) at the same time from
files on the HD. With my IDE drive, there wasn't any noticeable
difference in duration between burning 2 DVD's simulatenously or just 1
DVD, but with the SATA drive it seems to take twice as long when I'm
doing 2 DVD's at the same time.

My DVD writers are on separate IDE buses so there's no conflict between
them.

Any ideas why the difference in duration with the SATA drive?

What OS do you use?

OS is Windows XP SP2.

In Nero I notice that the "Used Read Buffer" fluctuates from 0 to 100%
when I am burning 2 DVD's, whereas it's constantly around 100% when
only doing 1. It's as if trying to read 2 sets of DVD files from the
SATA drive blocks things up, whereas the IDE drive seemed to cope with
it fine.

Someone mentioned that it might be the PCI bus that's being flooded,
but the SATA drive wouldn't use that, would it? The motherboard is an
ASUS P5GD1-VM.