ALternator toasted?

[dvdevo]

My car died last night and i tried to jump it but still wouldnt start. so then i tried anotehr battery and it worked so i got a new one. But then i was reading the threads about alternator test. How i run the car idle, then take the neg out and see if it runs.

My problem is that the car idles when i take the negative out..but i reved it once and it died. I was too scared to try again, reving i mean. The car runs fine now, i drove around for 10 minutes, but i'm scared taht its my alt thats fux0r3d.