wait for it...
Still, if the OP's machine was going to fail, it would have long ago. If it is still running well, it's in its downswing years and will continue to operating for its designed lifespan without a problem.
^^^ this. If you had a Mac affected by the "capacitor plague", it'd have died a long while ago, or would at least be so faulty you'd know it.
Yep, 2x SATA I 1.5Gbit/sec hard disk drives.G5s HAVE SATA DRIVES