lyn - if you're driving Farley Mount is easy to get to, as all the other places that have been mentioned. Glad you found acorncup's link, which is excellent.
Parking in Winchester can be a nightmare, with really only the places to park, are in the main car parks. Does Giffard House have its own car park as that will make it easier. The one way system round the city dicates the way you go but as it is small, best to leave your car where you're staying to see the city and only use it when you go out.
Winchester College is a very famous Boys Public School which spreads out from the cathedral, the architecture of some of these houses is amazing - facing the front door of the cathedral turn right and wander the streets (Wykeham Arms nearby).
Don't forget King Alfred burnt his cakes in Winchester and Arthur's legends abound here too.
Another place to eat in the city is the Chesil Rectory - one of the oldest buildings and great food.
Stop me rambling someone!
You can see why I like living here...