What is a good Video Card for a HD Monitor

I have a Windows 7 Dell Computer and an LCD HD 24" 1920x1200 60hz Gateway 24" monitor from a previous PC. The picture on the HD Monitor isn't nearly as sharp. The old Gateway card was 256mb and so is the new Dell's. What to do

Whats your budget?
I would go with high end cards maybe a 58xx series from ATI as they give heck of a perfromace for gaming and HD video, And they have a native HDMI port, or go with Nvidia their latest cards GTX series shoudl have HDMI, also you'll need a HDMI cable to get a clear picture, If you in for only HD movies and such go for a 4670 less than 100 bucks and has HDMI and plays HD material just fine. (not so good for gaming)
When you buy a HDMI cable dont go for 100 bucks one just take off and buy a 5 bucks one i have compared with my friends Monster cable on the movies and games we tried was the same picture on both of them but the saturation was better on the Monster cable on console games.

I'm not going to be using it for gaming. Just for Excel sheets, some movies, clearest reading; want a clear picture, not a fast-change picture. Sorry this sounds boring.

First and obviously, check your settings, both in Windows and on the monitor itself to make sure you are viewing in the full 1920x1200 resolution and that the picture fits the screen precisely. Flat panels do not provide a clear display if they are run under their native resolution or if the picture is incorrectly sized.
Check the cable, make certain it is fully seated and the pins are clean and shiny.
As a last resort, the HD4550 is made for your needs, they even come passively cooled helping to keep your nice new system whisper quiet while having plenty of decode muscle for even Blu-ray playback.