I guess it could work as a second machine. If you put more RAM in it. 🙂
And give 10.2 a try. RAM leaks and sluggishness is supposed to be a thing of the past. But honestly I can’t imagine trying to use AE with 8 gigs. I’m doing corporate stuff in FCP, AE and motion. 32gigs doesn’t seem like enough sometimes.
If you go iMac, get 32gigs RAM, i7, and the top GPU and you’ll be a happy camper.