Locking a MAC.


I work in a software company (we are software developers) where there are PCs and MACs, they all interconect through an ethernet. All PCs run Windows XP or 2000, there's a PowerPC 6300 running MAC OS 8.6 and a MAC mini running tiger. Since I'm new to MAC OS, I'm surfing Internet so as to learn as much as posible. I've already managed to connect every computer to the intranet.
The problem I have is that every PC runs a program through which you register how many hours you worked in each of the various projects. If we don`t load daily how many hours we worked in a specific project, we might not be payed those working hours. Hence our monthly pay decreases, since we are payed for each hour worked on a project. I've already finished a program that when I turn on my PC, loads Windows XP/2000 and then shows me a screen. In this screen (is a sort of grid) I fill in every task I did the day before, every hour worked. But, unless I save the changes made on it. I'm not able to work with the PC. I did this by using SetWindowHookEx()) in a Windows environment. It works very nicely. But I have work mates that are graphic designers and they work with MAC's. Therefore I must develop a software that works identically (It must do exactly the same) and that runs on MAC OS X. Most probably we'll buy another MAC mini.
I hope this gives you and any other who can help a perspective of my problem. Basically, the idea is to turn on a MAC, manage to automatically load my software, "lock" the MAC until my work mate fills in the amount of hours worked, and then allow him/her to work as always.

Mac not MAC. MAC means something totally else in computing.

Anyway, Preferences > Security allows you to lock the computer and you can even set times for it to sleep, shut down and wake up. In Preferences as well.
Mac = Macintosh
MAC = Media Access Control (MAC Address on your NIC) :p

It sounds like you're looking for a timeclock of some sort. I know what you are talking about. Check Version Tracker or MacUpdate.