You should be able to get an external USB enclosure or converter, remove the drive from the PC and fit it to the enclosure and plug it into a different system to read it. Alternatively, you can download something like Knoppix or a similar Linux distribution, put that on a USB drive and boot the PC from that so that you can get to your files using Linux. The question is what you want to do next? Do you want to get this system up and running again or do you just want to copy old files off this drive?
Make sure to get a USB converter that allows you to fit a drive with an IDE interface, as I'm sure that this drive predates the SATA interface. Google 'IDE to USB converter' for some suggestions.