+1 agreed! If you could fit it into your budget, a new Behr radiator will only run you another $140-175 bucks. Plus it might be a good time to replace the plastic octopus fitting on the driver's side of your engine block. If I'm not mistaken, M42's don't have the plastic "Y" fitting on the back of the head, so no need to worry about that. If you were to replace the radiator and "octopus" fitting in addition to the other components you've listed, you'll have a completely refreshed cooling system which is a huge weight off your shoulders.
Now most people will tell you that you need to remove the intake manifold to access the octopus fitting. Personally I don't recommend going that route. Instead, it's much easier and you'd be killing two birds with one stone if you were to simply remove the alternator and oil filter housing and attack it from the front. Oil filter housing leaks are a common issue with these engines. So with it removed, you can easily replace the two o-rings and paper gasket(5 bucks tops), and that will be another crisis avoided. Plus if you have the radiator out, it will give you even more room to access the alternator, oil filter housing and octopus fitting.
As Pete mentioned, a new belt and hoses are a good idea too. You'll have the belt off to remove the alternator anyway, and the hoses off at the thermostat, just leave them attached to the old radiator and yank the whole thing out. I know it sounds like a lot, but it's so much easier when you just knock it all out in one shot. The most important thing is BLEEDING THE AIR OUT OF THE COOLING SYSTEM. Let me stress DON'T FORGET TO BLEED THE COOLING SYSTEM! I can't say it enough, ALWAYS BLEED THE COOLING SYSTEM. Once you think it's bled, BLEED IT AGAIN and MAKE SURE IT'S BLED PROPERLY.
So, now that we've established that you're going to need to bleed the cooling system because all of the coolant is going to dump out of the engine when you remove the t-stat and water pump, all the more reason to replace the radiator, hoses and octopus fitting. This will save you from having to re-bleed it again and again later.
Removing the water pump can be a PITA. Never try to pry it out. If you look at the water pump as it's installed on the engine, you'll notice two unused threaded holes on the face. These holes are meant to be used to extract it from the engine once you've removed the bolts. Basically, you remove the bolts, then thread them into the extraction holes and the water pump is supposed to slide forward and out of the engine. However, it never works that way.
90% of the time, those extraction holes snap off and your water pump ends up in pieces and stuck in the motor. That's okay, DON'T TRY TO PRY IT OUT. You'll cause more damage than good. Instead, take a big ass pair of channel lock pliers, grip the water pump housing and twist it side to side(clockwise, counter clockwise) while slowly pulling it forward and out of the engine. When you go to install the new one, put some silicone grease on the o-ring to help it slide in without getting cut.
Here's some helpful links:
cooling system rebuild
http://www.318ti.org/forum/showthread.php?t=18066 oil filter housing
http://www.318ti.org/forum/showthread.php?t=20854 BLEEDING THE COOLING SYSTEM
http://www.318ti.org/forum/showthread.php?t=27983