Mo ACL surgery

I've had a reconstruction 16 years ago on my left knee - a few cartilage ops on both knees later, i'm now due a reconstruction on my right knee.
I've put the operation off until May 2010 to allow for work commitments - i'm strengthening the knee joint as best I can 'leg extensions' 'reverse leg curls' etc, i find the leg raise causes discomfort, along with seated squats - this could be the cartilage damage diagnosed, and the PCL torn but not snapped.
Has anyone more exercises they find beneficial?

Regards

Mo