ASP: Removing Harmful Characters from User Input

  Response.Write("Hello, " & RemoveBadCharacters(Request.Form("UserName"))) 
  Response.Write("<BR>This is why you received an error:") 

  Function RemoveBadCharacters(strTemp) 
    Dim regEx 
    Set regEx = New RegExp 
    regEx.Pattern = "[^A-Za-z0-9_ ]" 
    regEx.Global = True 
    RemoveBadCharacters = regEx.Replace(strTemp, "") 
  End Function

(http://msdn.microsoft.com/en-us/library/ms526004%28v=VS.90%29.aspx)