Older Mac vs new something else

Macbook's are great machines. I've had my Mid-2010 MBP since my freshman year of college back in...well 2010 and it's still going strong. If you treat them right and are willing to invest a little TLC into some relatively cheap and painless upgrades (RAM, SSD) they pay great dividends. Plus, if you aren't super techy, OS X does a lot of things really well under the hood that makes life easier for the user.

You should never have to defrag and, while I always recommend some sort of antivirus protection (at the very least a passive scanning app), the risk of getting a virus is much lower than on a device running Windows.

That being said, anytime you pay for an Apple product, a solid third of the price is just for the name. A part of that name price does include the engineering and R&D that goes into creating the product, as well as customer service (if still under warranty.)

Unless you are really into Mac for one reason or another (as I am), you should look into what you can get for the same amount from a PC. Weigh your options and maybe narrow it down to one or two alternatives to a MBP. Then see if you're still interested in picking up a $500 computer that's over half a decade old. If you are, go for it.