Go for it if you can get it very cheap or free.

Drain all fluids as mentined, but also flush all.

As to the trans, drain it, fill it. Run it for no more than a minute and drain again. Then flush it. If major corrosion hasn't already happend, you might just come out good (though if the friction disks have soaked water, their life will be greatly shotend). If all seems well after it's drivable, flush the trans again after about 1k miles.

Don't forget the fuel tank, brakes and rear end. They've already been mentioned, but these seem to be the most forgotten areas.