Upload & Sell: Off
PCs *are* a target for maleware, spy-bots, spam, etc. It is well known that Mac computers use an OS that is inherently difficult to write spam script for.
Spam has very little to do with OS and everything to do with how many people have access to your email address. If you have been having problems with spam in your mailbox it is likely because your email address has been distributed to multiple spam lists, and/or you have not set up your spam filters properly in your email program.
You are right that there is LOT more malware written for the Windows OS than there is for OSX, and that is because a vast majority of the world's computers run on Windows. OSX, which is based on Unix, is also theoretically more secure than Windows is, but that gap has narrowed a lot over the years. If you are running Windows it is essential to run antimalware software, to have your security set up right, and to be judicious about visiting unfamiliar websites and clicking on unfamiliar links. And if you are like me, confine all or most of your web browsing and internet activity to a virtual machine runnning Linux on a Windows host. It is trivially simple to do this nowadays, and the extra security you get with playing only in a tightly controlled sandbox makes you virtually impervious to the majority of malware out there.
It is the price I am willing to pay for a machine that will better thwart the scumbags that infect computers.
Makes sense to me.
Again, I am speaking from years of experience. Same tasks, two different systems. Mac wins by miles.
My personal experience has been quite different, but I certainly understand your point of view.