This one is an Excel add-in that adds functions to Excel to analyze your trading and manage your portfolio. Notice that I'm not a professional trader or statistician, so the whole thing could be wrong, buggy or conceptually absurd. Probably it is all of the above.
I used the extremely good ExcelDna to write the add-in. You need to download it and follow the instructions in HowToInstall.txt on the attached zip file to use it. I based the formulas mainly on the work of Ralph Vince. Please buy and read his books on money management as they are wonderful.