That playlist is directing iTunes to find them from the LW download folder. So ... chances are that's where they are on the old computer.
For fast & easy access, go to your LW Library window, select Saved Files folder & press the Explore button. Sample image here: Using Library Explore button to access downld folder (click on link) & the folder will open up for you.

You could also search .mp3 on all drives of your old computer just in case.