I took a little more time reviewing the owner's manual and there are a total of 6 SATA ports on the motherboard of the XPS Dimension and it specifically mentions using CD/DVD drives on SATA #4 and #5. 

Well, I don't think the drives will work any faster than advertised, but the through put of data for a SATA line compated to a 40 pin EIDE cable should be much faster, which is why SATA was created in the first place as far as I know.  SATA I being 1.5 Gb/s and SATA II 3.0 Gb/s.  The burners at Plextor only utilized SATA I, but from a novice like myself it would seem logical that data would be transffered faster, thus eliminating a chance of buffer underrun etc.  I realize it doesn't change the burn speed.

it's an intel chipset.  you can run the intel chipset ID utility to get the exact storage controller in use.

 

you don't really think sata is going to make the optical drives faster do you?

just FYI but HDs can't even really sature ATA6.  Let's consider a 52x optical drive (52 times 150kb = 7800kb ~ 7.8mb).  An exceptional HD by contrast might sustain 70mb or so.  The only benefits to sata optical drives in my opion are

 

1) work with systems that no longer have IDE/PATA ports

2) better chance of support hotswapping.

Well, it turns out, the XPS 400 only has 4 SATA Ports (0 thru 3), I had mistakenly looked at the XPS 410 manual.  So, I'm still back to square one, because the manual does not specify what SATA Port #2 and Port#3 can be utizlied for.  The chipset is an Intel 945P.

I added a Pioneer DVR-212D SATA to my XPS 400 after the BIOS would not recognize a second DVD/CD burner on PATA-1.  Unfortunately,  the BIOS doesn't recognize the new SATA drive either and beeps on bootup.  If I bypass the error by pressing F1 Windows XP Media Center 2005 recognizes the SATA drive just fine as does the Intel Matrix Storage manager.  Here's what I've noticed about the XPS 400 BIOS:

 

1) Will only recognize a drive on PATA-1 if the drive's transfer mode is UDMA Mode 2 or lower.  If the drive is UDMA Mode 4 (like the Pioneer DVR-112D) the BIOS can't see the drive and reports an error on bootup.  If you disable the PATA-1 drive in the BIOS the computer will boot without error, but the drive on PATA-1 will be set at PIO transfer mode and perform everything slowly.

 

2) Adding a SATA DVD/CD drive on either SATA port 2 or SATA port 3 (I have HD's on port 0 and 1)results in the drive not being seen by the BIOS (even when it's enabled in the BIOS), but it will be seen by Windows and function properly after you get past the BIOS error on bootup.

 

I wish Dell would fix the BIOS on this machine, it is an XPS after all and shoud be a liitle more tweakable.  My daughter's Intel motherboard using the nearly identical chipset (945G/ICH7R) has no problem recognizing DVD drives on either the PATA-1 or SATA ports.