Don't worry about the majority of the small squeaks and rattles, you will always get them from a saxo.
If you have got more signifcant knocks, check you suspension components for any excessive play, droplinks, wishbones, track rod ends etc...
Have a good look at your rear beam, do the rear wheels have a lot of camber (slightly inward at the top)? Jack the car up and try and wobble the wheels at the top and bottom. Look for excessive movement.
Other common problems include water leaks, usually from the aerial or the sunroof. You will definately know about this is the footwells in the front are drenched after a lot of rain!
Rust under the arches etc.. , can be fairly easily solved and further prevented (if not serious rusting) by using hammerite and/or underseal.
Also check your oil, and all fluid levels, generally give it a good service and the car will run a lot healthier.
