Sub t()
RangeFindReplace [A1:B500], ">", 0, 0
End Sub
Sub RangeFindReplace(theRange As Range, Operator As String, vFind As Variant, vReplace As Variant)
Dim cell As Range
For Each cell In theRange
Select Case Operator
Case Is = "="
If cell.Value = vFind Then cell.Value = vReplace
Case Is = ">="
If cell.Value >= vFind Then cell.Value = vReplace
Case Is = "<="
If cell.Value <= vFind Then cell.Value = vReplace
Case Is = ">"
If cell.Value > vFind Then cell.Value = vReplace
Case Is = "<"
If cell.Value < vFind Then cell.Value = vReplace
End Select
Next cell
End Sub