Accept numeric values only in a textbox

It validates the entries of a textbox while it is being entered, and allows only one instance of the decimal point(period) to be entered. Please vote and leave a comment so that at least i know im doing something right. =)

//**************************************
// Name: Accept numeric values only in a textbox
// Description:It validates the entries of a textbox while it is being entered, and allows only one instance of the decimal point(period) to be entered. Please vote and leave a comment so that at least i know im doing something right. =)
// By: Tristan B. Astillero
//
// Inputs:It has 2 parameters: e.keychar(eventargs) and the textbox control.
//
// Returns:Returns a boolean value indicating if the event is handled or not.
//
// Assumes:If you have any suggestions or encounter an error I would appreciate your comments. Thanks. I it's simple but hopefully this will garner me some votes. =P
//
// Side Effects:None to my knowledge(so far).
//
//This code is copyrighted and has// limited warranties.Please see http://www.Planet-Source-Code.com/vb/scripts/ShowCode.asp?txtCodeId=932&lngWId=10//for details.//**************************************

Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
 e.Handled = NumbersOnly(e.KeyChar, TextBox1)
 End Sub
Private Function NumbersOnly(ByVal pstrChar As Char, ByVal oTextBox As TextBox) As Boolean
 'validate the entry for a textbox limiting it to only numeric values and the decimal point
 If (Convert.ToString(pstrChar) = "." And InStr(oTextBox.Text, ".")) Then Return True 'accept only one instance of the decimal point
 If Convert.ToString(pstrChar) <> "." And pstrChar <> vbBack Then
 Return IIf(IsNumeric(pstrChar), False, True) 'check if numeric is returned
 End If
 Return False 'for backspace
 End Function