I am a PC guy trying to break into the Mac world. I want to buy a used Macbook off of Craigslist but I am concerned about the possibility that the previous owner may have intentionally or unintentionally installed malicious software like a key logger or trojan horse. I know Macs are generally safer but that doesn't mean there is no risk. If I am going to be doing things like online banking on this new computer, I'm not taking risks.
On a PC, I would reformat the HDD, reinstall Windows and reinstall each individual application using the original installation media. This is a tedious process, possibly taking several hours. Is this the best way to secure a Mac also? Since I am buying the computer used, I may not necessarily have the installation media. Is there a way to automatically reinstall all the applications (i.e. Time Machine)? Am I being overly cautious?