If you're an Excel user you may want to try your add-ins 'analysis toolpak and analysis toolpak- vba'(if these haven't already been added in). To do this go under tools and select Add-Ins....put a check by each one then hit ok. After you do this you should be able to go back under tools and see 'Data Analysis' at the bottom. You can get to the regression analysis from there.

Below is a link to a free 30 day demo of Analyse-it.....an Excel based statistical package (well...actually I believe it's an add-in).....honestly I haven't used it but I've read lots of good things about it and I'm ordering a copy for myself.  I think w/ the 20 % discount you can get a full seat for $100.....the student version is like $25.... analysis included in the package are Descriptive statistics, ANOVA, group comparisons, multiple linear regression & correlation.

I hope this helps.

http://www.analyse-it.com/regression-analysis_a.htm

Also, here's a link to a 5 day trial version of DOE Pro XL

http://www.sigmazone.com/downloads.htm

See also the thread
Thread770-82805
in the "Engineering Sreadsheets" forum, where I have just placed a post.

For regression or other statistical analysis, I personally like to use software like Mini-tab. The reason is that is allows analysis beyond regression. e.g. Scatter plot, distribution of data analysis.... even hypothesis testing.

If it's jus simply simple regression, I guess Excel will do the trick. Hope that it's helpful.