That PSU will run a GTX 460 no problem. I'm using a 5870, which uses a fair bit more power compared to the GTX 460, and I had the exact same PSU as you've got for 5 years before now. It worked just fine.
Bear in mind, the fan on the PSU can get loud under load, and it will probably die after a while. That PSU got to the point where it was finicky about when it would turn the computer on. That did it for me, so I replaced it with an awesome 750-watt corsair unit.
Hopefully you'll have better luck than I did.