Beginners Astrology software (Mac and PC)

Hi there

I haven't been around these parts for quite some time because I've been busy with more mundane matters. However, I'm getting back into planning rituals; this time I'm going to try to learn a little bit about astrology so I can plan my Planetary magic rituals a little bit more accurately. Can anyone recommend some good, easy Mac apps or PC software for this astrological purpose and some really good beginners astrology books?
I'd appreciate any assistance.

Cheers, Whitewolf