I have an Open Office Calc and (converted) Excel 97/2000/XP spreadsheet that, if you enter the attacker and defender dice, will give you the deviance from the theoretical values.
I'm in beta testing phase. I have two players on another site (one for Open Office and one for Excel). I could use 2 beta testers here (again, one for Open Office, one for Excel).
First two serious replies by PM or email will get the spreadsheet to play with and see actually how fair it is!

(I will need your email though, so if you PM me, please provide it)
PM or email me @
atomicslug@hughes.net
experienced and patient players only please (you have to enter each of the rolls manually, but alt-tab comes in handy, and is quite usable).