Bigger isn’t always better. If you’re lusting after a 20- or 21-inch monitor to replace the old one on your desk (especially if the old one is a CRT), let me offer a different suggestion: Get two smaller flat-panel monitors instead.
The advantages of two monitors are overwhelming. You can actually open two separate windows (a Web browser and an e-mail program, for instance) and work with them individually instead of having to fuss with arranging them on the screen or constantly minimizing one to get to the other. And you get more bang for the buck: a pair of 15-inch flat panel monitors should cost less than a 21-inch model, but give you much more of a productivity boost.
Most modern video cards, even dirt-cheap ones, support multiple monitors. The settings page in Control Panel’s Display dialog box is easy to use, and even lets you configure which monitor is left and right:
Next to adding more RAM, this is the upgrade I recommend most.
Ed Bott 
First, I very much agree with this. I have two monitors at home (18 LCD, 21 CRT) and two at work (2 x 19 LCD). I couldn’t imagine going back. The really nice thing about 2000/XP support for mutli monitor is that it can be extended further. For a while I had a spare PCI video card in for 3 monitors. Right now I am considering an SLI motherboard simply so I can have 4 DVI connections all at once.
I know there has been research showing two monitors makes you more efficient. I would have a hard time going back to one.
My notebook makes me claustrophobic. I’ve had two monitors on my home computer since shortly after I installed Win98SE and read somewhere (probably an Ed Bott book) about multi-monitor. The office followed shortly thereafter. I can’t imagine getting anything done with only a single monitor. Until my CRTs croak, I’ll be tied to them, but after yesterday’s visit to one of my clients with dual Dell widescreen LCDs on each desk, my CRTs may come to an untimely demise.
I couldn’t agree more. I actually have 3 at work (24″ widescreen LCD, flanked by 2×21″ CRT), and it absolutely drove me nuts only having one at home (20″ LCD).
I finally added an inexpensive 17″ LCD to home, and it is so nice to finally have. Although, now I’m missing that third one… 🙂
One thing I will add is that I am in the situation of having different-sized and thus different-resolution monitors. It is very workable, but I would recommend getting them all the same size/resolution and preferably make/model if possible — and definitely set them all at the same height.
Great tip, and to take full advantage, consider using UltraMon.
I second the recommendation for UltraMon.
I’ve been using a dual setup powered by Matrox cards since ’98, and trying to work on others’ single monitor setups now feels like having one hand tied behind my back. The improvement in effectiveness and convenience is addicting. Having to work on a 15″ lcd feels like trying to work on a pda screen.
I can’t wait to see what it’s like with a dual-cpu machine powering a dual monitor setup. Just waiting for parts.
I feel confined with only 4 (19 inch lcd) monitors at home. I have 8 (19 inch crt) monitors at work. It is definately a one way street. Everytime I add a monitor, there is no going back. I am typing this on monitor 6 of 8.