I'm looking into buying websites with a decent ranking. If I buy one then the whois info gets changed to my info, will that affect the ranking? I've read that it can but doesn't always affect it. What's everyone's opinion?

Changing your Whois can affect rankings. I've seen, and other can testify, that changing the Whois can lead to a complete drop in PageRank.

Of of course, doh... I was just thinking af an address change but no change of ownership but how does Google know that, they're going to see it as a change of ownership if the whois changes significantly and of course that means reseting the domain score, makes sense.  Never had to deal with this though.