From what the OP described, I'd say any intel mac would do.
It's a question of how much do you want to spend, and how comfortable are you with "old" technology.
I recently bought a 2007 MacBook (2.0 ghz core 2 duo, 2 gb ram, 80 gb hard drive). I paid slightly over $500 because I bought it from a store. I could have paid less from craigslist or ebay. A friend bought the same machine for $200 on craigslist.
As for ports, it has 2 USB 2.0, 1 firewire, 1 ethernet, and 1 display port.
It is surprisingly fast given the age and specs. I wouldn't use it for gaming, but is great for "web surfing, music burning. And light data."
As for ports, you may want a USB hub if you have a lot of stuff.
Firewire is fast, but most things are USB.
The biggest issue will be hooking up extra monitors. Apple uses proprietary connections, so you'll need an adapter to go from the Apple port to the monitor.
Good luck!!!