I'm not sure how one can be a "better machine" for the OP's needs. He's not a power user. He just wants something to read emails and browse the net. His old Sony is probably perfectly adequate with a few free improvements like a better browser and Adblock...done.
If he chose to upgrade, a tablet of some type might be perfectly adequate. There are some very good tablets out there for a little money. I don't think he'd find a new Apple laptop to be worth it.
I use a hotrod laptop with dual drives for travel and a similar desktop at home. They're both Windows 7 systems because I can easily upgrade them as required and the software I run isn't available for Apples. They're both very fast and trouble free, and I use them all the time.
But, the OP doesn't need the kinds of systems that I have, so I wouldn't recommend them.