There are already some good accounting software available. If you need help (my domain knowledge : Accounting, Costing and Business Consulting), please call me on 9819384313. Also have a look at web-erp. It is a good package, though some changes are needed.
1. Are these packages GPL? 2. Can it import Tally data? 3. Will Accountants be willing to switch to them?
If the answer to all 3 questions are yes, then I guess that's a good enough reason to prevent this project from taking off ...
Rishi