Should be plenty adequate for silky smooth boxing.

Potential tears in the silk:

Windows XP - if you don't setup your video for horizontal span mode it won't work for crap on the 2nd/3rd monitors. I don't know how horizontal span works with 2 video cards, someone else may be able to speak to that.

Windows Vista - Horizontal span doesn't exist here, HOWEVER Vista handles video a LOT better on dual head systems than XP ever has, so you shouldn't have any problems there.

I'd suggest KeyClone and it's Maximizer functionality for splitting up the alt boxes. Running them at 1024x768 is fine, but then you are switching back and forth and you loose the seamlessness. I've been running two on my laptop at 800x1024ish and it's a LOT easier to interact with them now! Collection Quests aren't the pain they used to be (still a bitch to kill 3x the number of mobs to get the drops, btu thats just xp on the way) and doing things like interacting with npc's, trades, etc are tons easier.