It's a matter of bandwidth and cookies.
I work with the web a fair bit and typically flush my browsers' cookies and cache very regularly. You should do this regularly too, for your own privacy and security. But with this practice, I'd drive myself crazy having to repeatedly key in my mob wars numbers.
Also, I'm pretty tight with my network bandwidth expenditure, and am nowhere near Facebook's multi-server allowance to post and repost all graphics and text with almost sheer abandon.. Similarly, I don't like using online calculators because I don't want to use up other people's bandwidths, free as it is. Oh, did you know that you could also be tracked?
My Mob Wars Calculator is designed to be used on Microsoft Excel 2003 and above. Yes, I lose out on a bunch of functionality (from Excel 2007) and flexibility (from programming in say, PHP). But hey, you tell me if you like the Calculator.
If you've followed my versions up through the Mob Wars Discussion Board, you'd know that I've spent quite a few hours on this. I'm just going to unabashedly ask you to buy me a beer (click the BUY ME A BEER button) on the right bar of this blog. Thanks in advance :)
For those who do not have Excel nor other compatible means to use the spreadsheet, try out this link from microsoft:
Microsoft Excel 2003 Viewer
(and no, I don't know how to support this viewer if it fails for you)