Toyota Repair: 1993 Camry 6 cyl 140,000 mi, check belts, filter drain

Question
Had the oil changed and they said transmission fluid was dirty. My nephew changed the transmission fluid. Next time I had it in the shop (different place), they said transmission fluid was dirty and needed to be changed. That Saturday, on the radio Car Talk said dirty transmission fluid means transmission is going out. I don't detect symptoms of that, but what do I know?  To figure this all out, my son gave me car service for Christmas. I have an appointment 1/2/08. He had new struts and timing belt put on when he bought it for me at 99,000 3 years ago when I retired. What else will they want to do? I don't want it to be too expensive, much less do something that doesn't have to be done yet. (I'm feeling guilty because I got a verbal estimate on fixing the driver's window that doesn't close, and it's there now, with the bill going from $90 to $297 - and my son is paying for that too!) What is the 125000 check up (that's what they want to do to the car)and what in that can be postponed until specific symptoms? Please help me so I don't take too much advantage of my son's generosity.

Answer
All that is left to do on the 120,000 service is to change the oil and filter, drain and refill the coolant, rotate the tires, check the brakes, replace the spark plugs,air filter, check suspension components, exhaust system, check belts and hoses etc., most toyota dealer have a special going on most of the time for this service and it shouldn't be more than $300, by the way ask them to completely flush the transmission with a machine to get all the old fluid out and replaced with new fluid, this will add about $150 to the bill but it's worth it, other than that they may try to sell a lot of other stuff which may be worth doing but not be needed urgently, unless it's a safety item like brakes or something that can cause engine damage it can wait.