97 Passat heater core

I am replacing the heater core in my Passat VR6, and was wondering if anyone knew of the easiest way to do it. I have the center console torn out, and was told by the dealer that I would have to drain the air conditioning. Is this true? Also, in the near future, I will be replacing the main water pump, the front motor mount, the pcv valve, and the serpentine belt. I am trying to find quality parts for this car without going to the dealer, and am afraid if I go to the local parts store I will get junk. Any insight that you may have would be great. I have only owned this car for 3 months and am finding out that doing the extras that I would want to do obviously will have to wait, at least until I can get some of the necessary problems out of the way. Sorry for the rambling.

First thing get a good manual, I like Bentley's. You do not have to discharge the A/C to get the heater core out. There are six clips that hold the two housings (A/C & heater) together. Remove them & the two 10mm nuts for the heater box at the firewall inside the engie compartment. You may also (recommended) have to loosen the dash to raise it up enough to get the box out. The back two & top clips are a pain & you won't get them all back on. The job is really difficult the first time you do it. It is very difficult to get the two box halves aligned when putting them back together, you may have to loosen the nuts for the A/C section.