You could go with a smith but I have always felt that free weights are safer than fixed plane motion such as a smith. I am not telling you to throw on 4 wheels and start squatting but maybe warm up with the bar in the rack and then adjust accordingly. Your own range of motion with not be the same as the smith and with free weight you will also involve more stabilizers throughout your entire body. You can really do a lot with a rack to be honest including shoulders, chest, pull ups, chins, etc. Now as far as resistance cardio equipment you may want to go more with a recumbent bike rather than an elliptical as I think you may benefit more. Treadmills are also really good but I always suggest an incline when on them to mimic running/walking in real life and to take the stress off your hips and knees. After a quick google search something like this is what I had in mind, now you can go a lot higher in price and get more options but that is really up to you.
http://www.fitnessultimate.com/P1113...Squat-Rack.htm