My old power converter broke, so I am using one from another computer.

The one that came with the computer had an out put of 3.42 amps

The one I am using now has an output of 4.74 amps

Will this hurt my computer?

It should not hurt your computer at all, as long as the output voltages are them same, such as the +/- 12 V, +/- 5V , etc.. the current draw from the power supply is depending on the input impedance of the computer, the OHM's law. It is a better power supply than the old one.