There is a great post in O'Reilly's Answers that talks about when to use Excel and when to use R. I have been using a lot of R lately to perform some data analysis and logistic regression. R is a great tool for statistical analysis. R is also free and open source.
I am going to be doing some more blogging about statistics and using R (R-project homepage). There is a huge amount of uses with R and I'm sure I will only hit the tip of the iceberg. If you have experience in R please let me know and I would love to share your experiences.