Suggestions for a project (newbie)

Hi
I'm a student of computer science and i'm working on project. I never worked much in exel but programming shouldn't be a problem i just need to learn the syntax.
What i need is some suggestions on how to get started.
I need to make an exel program(client) for office workers(3 of them) that would be able to store tables ether in a database or just keeping it in the file(it's actualy not a lot of data)
What trubles me is that all 3 users wan't to use the program at the same time. By editing their own table they would be editing the main document that is (shared to all of them).
And if one of them edits a cell the other two must get an update ASAP!
Its basicily an employers list with some properties like % of enployment and other stuff.
The clients must be updated at all time so that situations like an employer beeing employed 100% by one of them and at the same time the other client employes him additional 50% witch can't happen.
So they need to be able to edit their own table witch after saving or pressing a button takes the data and stores it in a shared database. Each of them have diferent fields and cells depending on the office department.
To complicate things a bit more i need to keep history of all tables (edits) for 3 years!
At first i was thinking of simply making a exel shared file so all three can edit it over the local network. But i don't know how to keep track of history, Setting up a database could work but i guess i would have to implement some synhronization since more clients can't read/write the same cell at the same time or some values may get overwriten.

Any ideas (concept) on how to get this done without complicating too much??
The program has to have a REALY friendly interface so that office workers woun't have problems working with it.


I thank you in advance!

I would solve this by using 2 tables in Access that you access in Excel. Then every time a spreadsheet user makes a change, you would log that change in the table of changes and then update the value in the employee table. I have done this a few times but don't pretend to be able to give you all the things you must do to do this but you should be able to find examples on this forum. The beauty of this way of doing it is:
1. Users enter data in Excel which they are quite familiar with.
2. Data viewed in Excel is actually read-only because it is ultimately stored in Access. Actually, everything in your spreadsheet could be read-only. When they commit the data, you would have to run code to update the table in access. You would also update the changes table with your changes.
3. Upon opening the file the access tables should be refreshed to get the most recent version of the data. I may have an example of the code if you can't find anything on the subject. Good Luck.