In order to improve our work efficiency, we will update our computer system. It will be closing down at 3.00pm tomorrow. Please note that all important data [has to be / will be] saved before this time. After the update, staff will be able to easily find data by inputting key words.

In order to improve our work efficiency, we are going to (going to is better because it is a fixed plan) update our computer system. It will be shut down at 3pm next Wednesday. Please note that all important data should be saved before this time. After the update, staff will be able to find data more easily by inputting key words.

In order to improve our work efficiency, we will update our computer system. It will be closing down at 3Pm tomorrow. It is essential that all important data be saved before that time. After the update, staff will be able to easily find data by inputting key words.