Charge GS3 with old iPhone Plug?

Hey Army,

I'm a proud new owner of the Galaxy S3 and I LOVE it! I can't believe it took me this long to see the light.

Anyways, my question is about using an old charger:

Can I charge my GS3 using the AC adapter (wall plug cube) that I have from my old iPhone (3GS)? Is that completely safe or should I just avoid the idea and buy an additional Samsung AC adapter?

(I'd like to leave the spare at work so I don't need to bring my charger back and forth, and I want the option of using the wall charger instead of just the USB from my computer)

Thanks!
BioDave