It depends on what a "crazy price" is
He probably needs a dual-processor setup (autocad is known to use dual processors quite efficiently). A nice videocard would benefit as well. A 9800 Pro (Sapphire) would get the job done. The RAM is fine. That's the only thing I can recommend: get a new motherboard with dual processors and a damn nice videocard.
He has to understand that AutoCad can only look/run so good...no matter what you have. If it's a huge file, it's a huge file. That'll slow any system down.