I'd like to have the A/C Compressor NOT come on with the Defroster as it is a little noisy. Will unplugging the Compressor have any ill effects on the car in general?

It won't defrost the glas as well. The compressor running helps take moisture out of the air and that's what you want to defog glass. [8D]

As for the windscreen staying clear, having just returned from a 1 hour drive I can honestly say that the windscreen stayed perfectly clear - even with the blower OFF. The side windows did have a very small amount of moisture on them but not to the point where vision was affected. The Hatch Window stayed clear as well, with the RWD off. My car spent the last 13 years in the desert, so mold developing in the system is very unlikely.

Bottom line, without the Compressor, the Defroster was still 95% effective.

In a dry climate, should have no effect. But if it is humid and warm, it will be more difficult to work with out the compressor running.

I do live in Oregon, where it rains quite often as it has been for the last 6-7 days. Although wet here, it isn't humid and warm. I'm not worried about mold at all.