I have no idea what the files were mock23... It could have been leftover from the internal software at Alienware. If it's on the respawn disc, that's going to be a problem I suppose. If you ever send the unit back you can ask them to reburn the respawn for you...
I would do a clean install from the windows disk, add the drivers then burn my own image with imaging software. Does your buddy have anything like Norton Ghost that you can use to make an image?
As for the cards, I'm not sure it would be worth the upgrade. If AW says you can just pay the difference then it might be worth it. The cards are the same with the exception of the onboard memory. That memory only comes into play with current games at very high resolutions and settings, but with SLI it may not be all that important.
My benchmarks are similar to those with the 256 cards, so it's not about speed. I held out for the higher spec cards just to try to future proof the laptop a little bit more as I don't tend to upgrade laptops and I wanted the highest specs available when I purchased.
Maybe you can send it back, have them upgrade the cards and reinstall the OS and burn you another respawn disk while they're at it...