Note that the Radeon 7000 is originally specified to max out at 1280x1024 on DVI. It _might_ do 1680x1050, but to be safe, you should go at least with a 9000 series chip (9200, 9250). For a few dollars more than those, the minimum choice for a current-generation (DX9) card would be a 9550SE.
NVidia cards are a bit luck-of-draw, because of NVidia's high resolution signal quality issues on the integrated DVI transmitter. That said, at work I run a Dell 2005FPW from an AOpen FX5200 without any problem, alongside a 19" CRT from the same card's analog output. I don't know (nor care in this case) whether the card is running a reduced-frequency mode to compensate.
As for color calibration: Running from a DVI signal gives you most accurate reproduction of the supplied picture. Calibration will have to come from the graphics card's gamma curves, simply because on DVI, the panel does not do ANY image processing whatsoever - the only adjustment is backlight brightness.