DVD access causing lag, audio/video stutters

Can't figure out what's going on here.. any access to my CD/DVD drive, including even opening/closing the disc tray, is causing massive lag in the form of seeming total suspension of all activities, audio and video playback stutters and freezes.

Quick system rundown:
Device in question is a Lite-On LH-20A1P 20x DVD+/-RW
Asus P5B-VM mobo
Core2 Duo 1.86GHz
2GB 667 DDR2 ram
Asus EN7600GS Silent 256MB vid card
One WD 250GB Sata3 HD
One WD 250GB IDE HD
Some wireless NIC on a PCI slot
SB Live 5.1 (imported from the old computer along with the NIC and the IDE HD)
PSU came with the case, listed as 420W on the bill, actual labelling specifies 450W with 28A on the 3.3V rail, 34A on 5V and 21A on 12V
Also running 2 8cm fans in the PSU, 8cm CPU fan, an 8cm on the side panel and a 12cm on the rear.
Running XP SP2

The exact issue is such that almost any activity on the drive will cause these stutters and freezes.  Open the tray, watch the mouse jump around, pop in a disc of tv episodes and watch windows crawl to a halt as it tries to load thumnbails.. and yet watch those same episodes off the disc and experience only the occasional skip, particularly when resuming from a pause.

The drive is currently on the end of the IDE cable, jumpers set to master with the HDD set to slave on the middle connector.  The mobo only has one IDE connector.

First thought was that the CD/DVD drive was bad, so I popped in an old one, same issue remains. 

Perhaps it's a PSU issue, but I have no direct way of testing that right now, and it seems rated high enough for my system by any calculator I can find.  12V could be higher than 21A, but it doesn't seem to be horribly low to me.

Checked into the transfer mode.. kind of odd to me.  Under IDE ATA/ATAPI controllers I have a 2 port SATA controller, 4 port SATA controller, then four IDE entries as follows:

Primary IDE Channel
Primary IDE Channel
Secondary IDE Channel
Secondary IDE Channel

.. remember I only have one IDE connector in this thing.  Maybe just something I don't understand about this sort of thing.

Anyway, the first, third and fourth of those entries all describe Device 0 and Device 1 with Transfer Mode - DMA if Available, and current transfer mode - Not Applicable.

The second of those entries (second 'primary ide channel') lists
Device 0 as.. device type: auto detect (grayed out), transfer mode: DMA if available, current transfer mode: Ultra DMA Mode 5.
Device 1 as.. device type: auto detect, transfer mode: DMA if available, current transfer mode: not applicable.

I honestly don't know if this is correct or not.  Any thoughts?

Lack of DMA usually causes problems like this but if the drive's using Ultra DMA Mode 5 that's not the issue here.

You said there's only one IDE port on the motherboard, and you have the optical drive as its master and a hard drive set as slave? It's strange how it's not showing up as Device 1 in the IDE channel.

Is your operating system installed on the SATA HD? If so, try booting with only the optical drive and the SATA hard drive connected and see if the problem's still there.

OS is indeed on the SATA drive, unplugged the IDE HDD and the problem persists, same reading on the device manager.