Windows 7 - Question about audio connections

Hello,
im plannig on buying the logitech Z5500, I have onboard sound.
I found out that theres two ways to connect it to my computer, analog, wich is the normal case I think, and digital.

what is the difference besides that I have to buy a cable if I want to connect it digital?(It doesnt come with digital cablbles)
and what does it even mean, digital and analog?

thanks in advance.

The primary usefulness of digital is the ability to store, retrieve and transmit signals without any loss of quality.

does that mean that I should use digital? is it that much better?

Digital audio is only as good as the DAC used. Those z5500's may take a digital connection, but they are not digital speakers. If you are going to be using onboard audio, then digital may be the way to go as the DAC in those speakers is probably better than what is with the onboard audio.

You want those speakers to sound their best get a decent sound card and use analogue, as any decent sound card will have a far better DAC then the speakers.

I dont have enough money right now to buy a soundcard, so with my onboard sound,how do I get the best sound quality? Digital or analog?

Try both and let your ears decide.