If everyone has their own computer you can do this...
For the users who can a/e/d, go to their machine, and run C:\WINNT\system32\WRKGADM.EXE. (or where ever the WRKGADM.EXE is located depending on Windows version)
Click "Join" and browse to find your .MDW on the server. Then click "OK". That will save typeing all the commands in the shortcut, and it doesn't matter how they access the db.
On the machines that don't have the Work group set up, no login will appear, but it will default to "Users" group.(which you should set up as Rick39 described)
I did this almost two years ago, and it's worked great because the people who only need reports don't have to worry about passwords, and I don't have to set up a bunch of users.
A couple drawbacks:
If you have a lot of public machines, this might not work well. This is machine specific, and not user specific. If a machine is using your new work group, it will ALWAYS ask for a password no matter who's logged on.
Also, once a machine has joined your new work group this way, it will ask for a password no matter what db you try to open. So, if you use several different dbs, this could create a problem, or at the least, an annoyance.