When I started building my current box (January 2005) I had one 19" Princeton 1024x1280, which very quickly became 2. In November of 2005, I installed one 2405FPW at 1200x1980, and after seeing how much real estate it gave me, coupled with the fact that having 2 different resolution monitors did not give me the desired look for an XP expanded desktop, I opted for a second one in January of 2006.
Comment: once you work with 2 monitors, you will never want to go back to one. You should have a good graphics card, one with 2 DVI's. I started with a cheap ATI (Powercolor 9250 PCI w. 256MB, one DVI and one VGA connector) card, but kept having random problems with one monitor not synching at startup - finally sprung for a ATI X1800XT PCIE w. 512MB, and have never been happier.
I located 2 brand new Dell AS500 14W stereo soundbars on EBay which are designed to easily clip under each monitor and then I built a patch box to plug both soundbars into, converting the 4 soundbar speakers into 3 speaker channels (Left speaker, Center speaker [uses left soundbar right + right soundbar left speakers], and Right speaker). Maybe not as super as getting megawatt speakers, but I figure that is what the home entertainment system upstairs is for. My main concern was my physical desktop real estate, and these soundbars are out of the way under each monitor using space that would never be used anyway.