"several years old"
Should note that the Core2 processor has been out for several years (8!!).  In fact, it has been out since 2006.   It is a 64 bit processor.
Processor technology has slowed down a bit in development.   Anything Core2 or later is plenty fast for 99% of the users.
Where computers are gaining the most now-a-days is in the I/O channels.    I had a customer wanting to buy a new computer and I convinced them they don't need one and simply adding more memory (it had 2 GB, they maxed it out at 4 GB) and changing the hard drive over to an SSD or hybrid drive would make a world of difference.  They went with an SSD and were completely blown away with the speed difference.   Their laptop was a Core2 duo running at 2.2 Ghz.
And, as a System administrator of many linux machines, while harder to get malware, it is actually easier to take over.  SSH is not the most secure protocol out there. 
I love linux, but still don't recommend it for those that are not willing to put up with a learning curve.