To add to the last thread - although I love Astrolog and recommend it to all my students (when people are starting out learning astrology, the idea of spending hundreds of pounds/dollars/Euros on software is very daunting), I did recently decide I needed something a bit more powerful - with the ability to do medieval astrology, design custom wheels, use additional asteroids and so on.
I looked at Janus, Kepler, WinStar and Solar Fire. To be honest, there was ultimately no contest - Solar Fire seemed to me to be streets ahead of the others, and at a similar price.
For fixed star work, I'd recommend Starlight by Zyntara (
www.zyntara.com) - this software was developed by Bernadette Brady (author of Brady's book of Fixed Stars, and also of the superb "Predictive Astrology - the Eagle and the Lark") because no other software deals with her method of parans (Solar Fire comes close, but not quite).
For research purposes, Astrodatabank is a great investment, though not cheap - and I've heard good reports of Jigsaw, though I've not used it.