Which Processor Is Better? And Is There Much of a Difference Between Them?

I currently have a quad core AMD A6-3600 APU with Radeon(tm) hd graphics 2.10 ghz. I might get a used computer on craigslist with this processor: Intel Core i7-860 Quad-Core, 2.8 GHz. Which one is better and is there much of a difference between them? And would it be worth the buy on craigslist? ($400) Here's the craigslist link: http://richmond.craigslist.org/sys/3917701696.html

It looks like a good deal, and as far as I can tell it will be significantly faster. It hard to compare them because only synthetic benchmarks are available.