Good luck Nidge. I quit in April 2004, and now sometimes even have trouble remembering that I used to smoke. It just (now) seems to be such a NON-part of my life that I can't believe I would ever have wanted to smoke, if that makes sense.
No idea about Zyban, though. Just wanted to add my 2cents about the "helpful" information other ex-smokers sometimes give. You hear lots of people saying things like 'Oh, I quit 20 years ago and some days I STILL want a smoke!', like as if they're trying to warn you that for the rest of your non-smoking life you're doomed to always having that urge.. Not always true.
I don't want one. Don't want to smell anyone else having one. (And wish I could build a time machine to go back and smack the stuffing out of Younger KaySquirrel for ever trying one in the first place.

) So don't let those gloomy warnings bring you down!
Best of luck to you!