Dell XPS M1330 Digital Audio - 5.1 DTS/DD

Hi, With the XPS M1330 being quite a premium machine I would expect it to have a Digital SPFDIF connector or a dual analogue/digital jack on the headphone socket but according to the specification, this does not seem to be the case? Can the headphone jack be configured to output a digital audio signal that can be then fed into a 5.1 surround system? I realise it has HDMI output but again its not specified if this carries audio, and if it does if its just PCM etc. The problem I have then is my surround sound processor only have Coax and Optical TOSLINK inputs, the HDMI lead would have to be fed direct to my LCD TV. Would I have to buy some extra external soundcard to get Dolby Digital and DTS 5.1 sound? Cheers, Mike