Page validation strategy ok?

Can someone confirm the following as an acceptable overall data integrity strategy please? I am trying to protect against any kind of malicious scrpting or injecting attempt.

The situation: Only logged on users who paid a membership fee to join can add, edit, and delete their records via a ListView, and the steps I am taking to ensure no malicious entries can be made are as follows:
1. The  ListView fields accept only numbers or letters (no special characters) as enforced by RequiredField and RegularExpression validators.
2. In the ItemInserting and ItemUpdating events, I intend to do server side page validation like:
Page.Validate()
        If Not Page.IsValid Then
            e.Cancel = True
        End If
3. The data comes from textboxes in the Listview that users fill out, and the sql commands are al ...