Changing the drive is very easy. The only hard part is disassembling the console as you will need special tools to do so. Once the console is apart you will only have to remove the 4 screws holding the drive in place, disconnect the ribbon cable and power cable and reconnect to new drive. The other problem is that the drive will cost around $40 - $50 and most likely you actually only have to replace the laser pickup inside the drive which is only $15. If I were you I would replace the laser pickup but this requires taking the drive itself apart which is more difficult to do.
Or you could USB load games.