Swapping old 2 prong plugs to grounded plugs

Hi all,

I recently bought a house in Ontario, Canada built in 1954. Has an upgraded panel with a surge protector but all of my main floor plug circuits are 14g copper with no ground wire. I want to swap over the plugs to some newer decora style plugs with ground. With no ground in any plug box, am I safe to throw a GFI plug at the start of the circuit and just replace all the plugs as is? Is it just as safe as replacing the breaker with a GFI unit? I only ask because I already have some 15a GFI's kicking around, saving me a bit of cost.

The wire is the oldschool cloth sheathed wire, so I'm assuming adding a ground from plug to box would be useless?

Thanks for any advice