OK. I bought two Dells. 1920x1200 24" and 1600x1200 20". Both do portrait. I have 3 Macs Spanning across 3 screens. PowerBook to 24" VGA, G5 to 24" AND 20" DVI, Cube to 20" VGA and Apple Studio 15" 1024x768 VGA. PLUS the Dell's both have VIDEO inputs. The 24" has, composite (RCA), S-Video AND component RGB inputs. The 20" has composite (RCA) and S-Video inputs. Both have a 4 port USB 2 powered hubs. The 24" also has a 4 slot 10 type digital media card reader attached to the USB hub in addition to the 4 ports. Apple only provides two FireWire ports that Dell does not. Otherwise Dell provides a built in way to connect a lot more stuff simultaneously for no extra charge. I have had both for a month now and I am delighted.
The 24" cost me $1,111 and the 20" cost $616 including 8% sales tax. $1727. Apple doesn't sell a 1600x1200 anything. The 1200 verticle is more important to me than losing 80 horizontally on the Apple 20" that is 1680x1050. Reason for wanting the 24" is to display NATIVE HD video. 1920 is the minimum horizontal for that. The DivX HD TV I am watching on it is stunning - 350 MB per 40 minute episode.
BOTH do portrait 90° swivels on their stands. Tiger is the first OS X version to natively support portrait mode. It is part of the Tiger Display Preference widow to allow rotation settings no matter which way you have turned the screen.
Rotate: Popup menu: Standard, 90°, 180°, 270°.
You could do this with an Apple Display attached to a vesa mount for an extra $200-$500 or even a $1,000 extra. Dell lets you do it for no extra charge.
If you want to see them in action, watch CSI on CBS Thursday evenings at 9 pm. They are using Dell displays in the Las Vegas Crime Lab ALL THE TIME attached to their Macs and their PCs. Dell Screens, Dell Keyboards, PC and Macintosh computers. They also use PowerBooks.