I don't speak from experience, but from a somewhat similar dream. I have a Dell 2407WFP-HC, (24"), and ever since I connected it to my MBP, I've dreamt of putting in a twin on a DVI splitter. Go for the dual monitors! Beautiful twin aluminum sexiness, like Swedish Twins.
Okay, now that I've blurted, let me say this.
Like you, I'm a heavy Creative Suites user; I have been dual screening for years: one monitor for the palettes, the other for the work. Made sense back when the prime screen was 1152x870, with a 1024x840 on the side.
Now, it's a mouse-a-thon to get from one side of my 1920 over to the other side of the 1440. And while having every InDesign palette open helps, its a little like looking for that needle in a haystack to remember where I left the Text Wrap dialog. I still use the keyboard shortcuts to flash the palettes, so I can find them.
I wonder if that second 23" ACD would be more pixels than practical? Maybe get a 30", and a cheaper secondary. That, in combination with a Spaces workspace (when CS3 plays nice with Leopard), may be more practical?