Confused about LCD monitor support

I hope this is the proper place for this question. If not, please move it to the appropriate location.

I have an XFX GeForce 6800 (128 meg) with dual DVI outputs. Currently I'm using a 19" CRT monitor hooked up with a VGA -> DVI adapter that came with the card.

I'm going to soon be purchasing an LCD monitor that has a native resolution of 1680x1050 (20.1" 16:9 widescreen aspect). My video card supports resolutions up to 2048x1536, and I've already created a custom resolution for 1680x1050. But, XFX is telling me (via email) that my card will only support flat panel monitors up to 1600x1200. Now, I'll be the first to admit that I haven't been following LCD monitors too closely until just lately, but I don't see why there would be any difference in supported resolutions between a CRT and an LCD monitor (on the video card). Am I missing something?

I suppose that, technically, 1680x1050 is a lower resolution then 1600x1200. 1600*1200 = 1.92 million pixels, 1680*1050 = 1.764 million pixels. But, regardless, I can't see any reason why my card (or any card, for that matter) would support CRT monitors up to 2048x1536, but only up to 1600x1200 with flat panels. I was able to set my current monitor at 1680x1050 and 1920x1200 just fine, but, again, it's a CRT.

Any insight?