Have fun – it is Quebec city 400 anniversary this year.
References :
http://www.gothereguide.com/quebec+city-city/

-Museé de la Civilisation (a museum about human existance, how we live, what our future will look like etc.)

-Musée de Beaux Arts (Art Museum which used to be a prison. Some say it’s haunted by the people who died from capital punishment)

-Les Plaines d’Abraham (Plains of Abraham where the war between the English and the French took place. There’s also a really nice view from up there)

-Anywhere in Old Quebec (it’s the 400th anniversary so there are street performances everywhere)

-Festival d’été (Summer Festival from July3rd to 13th which include big names like Linkin Park and Feist. A $30 ticket is all you need for the entire festival)

-Fete de la Nouvelle France (New France festival in August celebrates Quebec. It includes a parade and free live shows)

-Lévis (A city across from Quebec City. You need to take a ferry which costs $5.40 back and forth. In Lévis you will find a historic Fort, a chocloate factory, and many other things which you can find out about at the tourism info place)

-Ghost Tours (A guided tour on all the possibly haunted places in Quebec City and the history behind it)

-Chutes Montmorency (tallest waterfall in the province of Quebec, even taller than Niagara Falls)

-Churchs

-Poutine and Crepe places (famous Quebecois food)

I’m sure I’m leaving something out. There are a ton of things to see and do there. Even if you just walk around old Quebec (the historical downtown area) you will find fortified walls (it is the only fortified city in North America), artillery parks, etc. Have fun!!
References :
I spent a month there last year and I just came back yesterday. I’ve done almost everything there is to do there lol.

http://monquebec2008.sympatico.msn.ca/MonQuebec2008/?module=grandevent&id=39
References :
Have a great time!