There is an Excel add-in called XLSTAT-Pro which does both discriminant analysis and PCA. When installed, it creates an extra pull down menu in Excel with several dozen multivariate statistical procedures.
For more information, including how much it costs, go to www.xlstat.com. I think you can download a free thirty day trial of it at this URL. I've use an old version of this add-in and I like it. I payed about $250 and it was worth it.