Help ?

I have an RM Pc (the ones that schools use to have) in our bar and all we use it for is to store music and play it for 3-4 hours in the evening.
recently it has flashed up a problem with hard drive which prevents it booting up
i tryed to find a replacement hard drive however the new ones have different connections to the old one which has the connections you would use in a standard pc to wire up a dvd drive or cdrom drive.
is it worth replace ing the pc altogether or where can i find a new harddrive
current specks are
windows xp
126mb ram
2oGB hard drive
any help would be appreciated