Have you already made a test load on the server? By default, it should be able to handle that amount of users simultaneously. Tuning the server is going to depend a lot on what your users are doing, ie. what table is more frequently queried, how much load you have on your server in the peak hour, etc.
So please gather some statistic info before trying to tune the server. Probably you can use it as it is by default, 80 users is not a heavy load for a Quad Core with 4GB. After you have measured the users experience, if needed, you'll now where to tune.
I'd suggest just leave it that way
Have you already made a test load on the server? By default, it should be able to handle that amount of users simultaneously. Tuning the server is going to depend a lot on what your users are doing, ie. what table is more frequently queried, how much load you have on your server in the peak hour, etc.
So please gather some statistic info before trying to tune the server. Probably you can use it as it is by default, 80 users is not a heavy load for a Quad Core with 4GB. After you have measured the users experience, if needed, you'll now where to tune.