It usually goes up before MacWorld. You might wait and see if there is anymore news regarding the backdating investigation - it dipped last week on news regarding the stock-options backdating.
I've been buying AAPL stock for a few years now. I opened a
ShareBuilder Roth IRA account when I started my current job.
You can deposit $4000 per year into a Roth IRA and ShareBuilder makes it easy to pick the stocks that you want to invest your money in.
I think I got into AAPL at $32 and my most recent chunk was at $72.