I don't see your obsession for setting it to 75 Hz. I thought pretty much all LCDs were meant to run at 60 Hz. If you goto your Display properties, then Advanced, then to the Monitor tab, if you have 'show only supported modes', then 75 Hz is not an option at 1680x1050. Granted you can probably force it to, but again, I don't see any reason to screw with it with an LCD.
Anyway I don't see how someone who can barely type a coherent sentence can have so much good computer equipment!
As for correcting the color, I don't really know.. I never got an answer to that question when I tried. There is some color calibration software, but it seems to be pretty profession level stuff and cost a whole ton of money. Can you tell the colors are off? Maybe your monitor color profile is messed up? I think it's the .icm file or something that would be on the Dell CD... you could try reinstalling it.