This depends hugely on the type of analysis you will be conducting. If you are only generating descriptive statistics then Excel will allow you to do this very well. However, if you will be calculating any statistical tests (e.g. t-tests, ANOVA's, regression) we highly recommend you do not use Excel for this - there are well documented errors and other problems with the formulas Excel uses to calculate certain tests. PASW (SPSS) is specifically designed to calculate such tests and will allow you to do so easily (and correctly!). We do recommend using Excel for data entry and graphing however as it does a much better job of these than PASW.