Smacking is generally bad unless all else has failed or it's administered very carefully. I mean it works - but so do non physical measures as well and they can lead to a lot less angst. I know my kids take removal of TV/Gaming privileges pretty hard, as well as time outs and giving of additional chores : they particularly hate cleaning the chimney...
The bottom line is discipline gently but firmly from the get go and you should be fine - a lot of parents who smack IMHO are those who have failed to instill discipline and have to resort to that when "all else has failed".
I will say noting Euphoria's post that that's a circumstance I can imagine where a short, firm smack would help solve the problem more than a grounding - and certainly better that than a 20 foot fall. A good example of the exception that proves the rule IMO.
Try to be reasonable... its easier than you think...
