Re: Order of ROBOT/EMPIRE/FOUNDATION
If you have the choice, I'd definitely recomend reading the robot series in order. That is:
1. Caves of Steel
2. Naked Sun
3. Robots and Dawn
4. Robots and Empire
If you care to, reading I, Robot and The Rest of the Robots first might be the best way to go, but it's not necessary. The Robot novels, though, should be read in order. Don't follow my example. I had Naked Sun and Robots and Empire, so I read Empire first.
And you should read the Foundation trilogy in order, of course. It's really confusing otherwise, believe me.