I some how manage without ever smacking also. My DS1 is almost 3 and even on bad days i could never imagine laying a hand on him. I'm yet to be in a situation where it may need to happen for his saftey. I use a lot of distraction, say things once and then try and pretend i'm concentrating on other things as a lot of the bad behaviour is for attention. We use time out but the last few times he has been refusing to stay there, i may try sitting with him during this time also. Lately he's screaming ALOT and a tantrum has been a daily occurance (we spent most of late last year without one at all). I think the definace comes and goes as they begin to test new boundries. I have the 3 books that BellyBelly mentioned and between them there are some great ideas

I know when my DS2 came along i did my best to include DS1 in everything we did. Make him feel a part of what was happening at the time, be it changing a bott, having a cuddle. I would always allow DS1 to touch/cuddle (within reason) his brother so he was not something to resent as taking attention away. Good luck i hope things settle for you.