Brain Storm: Electronic Signature/Document Routing

my next to projects involve e-signatures and document routing.

1 is a purchase order system. The other is a time sheet system. We have active directory, sql sever 2k, vs.net 2003 and w2k/xp machines so one thought is to use these resources and devlope a routing system.

I know there are also 3rd party software packages that do some form of document routing and e-signatures. I think adobe may have one.

I am developing this system for my company, so everything is inhouse. I have never done a project like this before so I am having difficulties determining how to go about this.

Another thought is this information would have to hold weight in court if internal disputes ever got that far. i.e. an employee sues for wages they were not paid, we have a report/document that proves they were paid accordingly.

How could something like this be secured, so each user can only see their information?

Thank you for your ideas.