About five months ago I bought a used MacBook Pro off craigslist for $800. 2.2ghz processor, can run both OS X and Windows 7, 250gb hard drive, 2 GB Ram, beautiful 15" screen. A very solid piece of equipment with the best OS in the world - Snow Leopard.
This will be my law school laptop for the next three years. I actually upgraded the HD to a 500gb for just over $100, and I may have to upgrade the battery at some point (currently it holds 2 hours of power).
But if you are a Mac person, this is fantastic and a great deal. Craigslist ftw. Just make sure you inspect any laptop carefully before buying. Some people try to sell stuff with cracks in the display, dead keys, etc.
Edit: Desert Fox may believe that any $500 PC is just as good as any Apple laptop, but that's like saying my 2005 Blackberry is just as good as my new iPhone. They both make calls and send text messages, right?
I happen to care about ease of use, not having to deal with viruses or malware, and not being pestered by constant Microsoft b.s. Using Windows 7 (rarely) on my MBP is painful enough as it is. I'm glad to pay a small premium to make sure Windows is not my everyday experience.http://www.pcmag.com/article2/0,2817,2352798,00.asp
But, if you like Windows then go for it. I'm just glad we have a choice.