if it states DVD+/-RW then you can do both spheros, but make sure when you order it that the guy on the phone confirms that......
the GTO is still better than the X800SE, the X800SE is 128mb of DDR.......the GTO is 256MB of GDDR3, that alone is worth the extra money.....
the X800SE has a 425 core compared to GTO's 350, but then im assuming that you cant actually compare the cores because they make their chips different to one another.....
the X800SE only has 350mhz memory tho, the GTO is 450.......
personally i feel the price difference more than justifies buying the GTO even at the stock speeds, and if it turns out you can unlock or overclock then its definitely worth it......
i have tested my GTO today on HL2 at its stock 12/5 350/900 just to see what happens, it copes just fine at 1024/768 with all settings on high except i had reflect world, not reflect all, 4xAA and 8xAF......and it runs Doom 3 at a reasonably decent rate as well......
i dont think you can undo what the Dell techs have done now to the pipes/vu, i think they really have completely crippled them by the sound of it.....but also its likely that the board isnt being given enough extra power to run anything more than what they let you have....it doesnt use a standard power connector....
if you want totally outrageous power with the best quality graphics, then take the PC with an X300SE (yes, 300, not the 800) and buy an X800XT or 6800 Ultra separately......
(just bear in mind the 8400 comes with 350w power supply, so dont go for a 6800 Ultra if you have 2 optical drives, 1gb memory, Audigy soundcard and other trimmings, go with an X800XT, the Ultra just might prove too greedy for your system to run properly.....
hope this helps
EDIT: just to confirm btw, the GTO is a dual DVI, Dell will ship a DVI-VGA adaptor if you order a CRT rather than a flat panel, but you cant hook two CRT's up to it, if u want two screens one must be a flat panel...and there is no TV-out, so if u need TV out then i advise taking the standard X300SE and buy an X800XT separately, or even order it from Dell.....(forgot earlier in this post that Dell do the X800XT on the 8400 again...lol)