Yes I believe you can, Tony. What I do is not allow it to start with Windows, which you can set in File > Preferences > Basic Options. You can also have it running but set your status as 'away'.
As I said, the pop up notifications are only available with the Pro version, but if you're using the free one, you get a sound when contacts come and go on and offline.
I'll be interested to see how you get on, as most people here don't like it, but I think it's much better than MSN Messenger.
By the way, most people that are on it from Pals, use MSN, so you'll have to register on MSN if you want to talk to us, which you can do easily through Trillian.