First connection help

Hi, I just got my Arduino today and I am having trouble getting started. I have watched a video tutorial on youtube (How-to Tuesday: Arduino 101 the LED - YouTube) which tells me to select the correct usbserial port. This is not an option in my menu, I only can view bluetooth modem or PDA sync. How do i get the Arduino software to recoginize a usb serial port? The LED i have hooked up is flashing but not according to the delays set in the blink example. Please help.

What OS are you using (Mac or PC) and what development board?

I am running MacBook Pro with Leopard. My board is Duemilanove ATMega 328.

Did you install the FTDI drivers? They don't always come in right. I think there's a tutorial here: http://www.arduino.cc/en/Guide/MacOSX look at step 3.

I just installed the drivers, but still the same options.