I don't want to start a Mac/PC debate. I am simply trying to offer a solution to the OP's problem. In over 20 years of Mac use, I have NEVER needed to even think about anything as complicated as Donny's post! My Mac's started up, did what they were supposed to, and stayed out the way.
BTW, Mac's aren't as prone to viruses and other malware not because they aren't worth it for hackers to try (though that might have been true back in the OS8-9 years) but because OSX is based on Unix, an enterprise level OS that was designed for security and flexibility. Plenty of hackers TRYING, these days. OSX's firewall and sandboxing are bombproof.
My point was that, a computer is a TOOL. Buy the most reliable tool you can get (the heck with the cost!) and all you ever worry about from that day on is the JOB, not the tool!