for monitors you have a few things to consider, image quality, price, resolution....i think thats it.
24" is a great size and resolution, with the prices coming down i think £250 is enough to get yourself a decent screen. samsung are usually good, they make the panels most other companies use!
usually cheaper monitors are older versions, even if it has basically the same info, ie 1900x1200, 6ms, contrast etc there is always something better in the newer panels (obviously) but you do pay for that extra quality. someone also mention about 8bit displays, which are able to display far more colours than 6bit displays and are therefore better at accurate display (with the right config as per manufacturer)
if i was buying right now i'd do exactly what you are, 24" 8 bit, i'd stick to samsung or dell as they have consistently produced good screens.
as for your graphics card it's fine driving the display at 1900x1200, games would be another matter though!it'd struggle with anything that came out this...last year.
for video it's best to stick to it's native resolution rather than stretching the picture. most vids could be played in a window at 2x resolution that wouldn't distort the image hardly.
hope this helps.