Using 2 Identites on iMac at same time

How can I use 2 identities on 2 different monitors on my iMac (OS 10.6.8)
at the same time?

Aloha, RogerRabbit

I'm not sure that you can do this. You can set up different user accounts and turn on fast user switching. If you've connected a 2nd monitor then your machine should auto-detect it and you may be able to do it via the extended desktop option but I've never tried so my advice is probably about as much use as a chocolate fire-guard! There are some very experienced guys on here and they may have a solution.

I don't think you can physically run 2 different accounts at the same time. The only thing I can think of is having 2 machines and use screen sharing to log into the first one with one user account while it runs a different account on the screen. I do believe though that you'll need Lion to do this - Older versions of ScreenShare don't support logging in with a different user than currently logged in.

...I don't think this option is very economic. If you have 2 machines you might as well run those and share files instead of sharing the screen