PhD candidate in electrical engineering. Apple is a joke to the research community. Companies like IBM and Microsoft perform real, valuable research that advances society and improves lives. Apple is a marketing company that has done nothing for the world. Therefore, I would never give them my money when it could be better spent elsewhere. Steve Jobs was a prick, and was not revered by anybody but the media.
That said, Apple puts out a good product. however, The virus thing is completely overblown. What it primarily comes down to is software compatibility. Most of the software I personally need will not work on Mac. Most people do not have this problem, though.
I absolutely loved Windows 7. I've dabbled with Windows 8, but eventually just customized it to be like Windows 7 (not hard to do).
I would highly recommend, more than anything, is getting a SSD instead of an HDD, and use an external hard drive for large storage. SSD is far and away the best performance upgrade for computers in the last twenty years.