I don't think OS matters a lot, but I'd say Dell is making a competitive monitor at a pretty good price. You can try to find those extra stackable coupons on ebay and get a nice discount on your purchase.
$379 for 24" Widescreen (1920x1200 resolution) is a pretty good price. If you're going to rotate your screen or need height adjustment, you may opt for the $599 version. The latter also includes extra DVI input, S-video, composite, HDMI, and component input on top of the standard 1 DVI & 1 VGA on the $399 model; thus can double duty as multimedia display too. I assume that you're a photographer, thus the built in multimedia card reader to the $599 model might also be useful.
You can keep the change for color calibration hardware. I'm using their 20" and have been very happy so far. If you need more info about what each input does, PM me and I'll be glad to help you.