yes if you have an aux out on your headunit ....get the cable plug it into your deck then run it out with the dual female plug to single male other side (this is 1/8 inch on that side) plug it into your soundcard done ...then to listen switch to aux setting and listen to your tunes
I use a Fujitsu Stylistic tablet PC on my road trips. My 04 Camry has a big hollow beneath the dashboard, so with a strip of velcro, the tablet fits perfectly there. I use it for GPS navigation, playing MP3, watching DVD (passenger) using an external DVD player placed under the seat, accessing the net wirelessly with a wireless card in the PCMCIA slot, ... The possibilities are endless - I'm also thinking of getting a webcam in the back to use for reversing.
The way I have sound from the tablet hooked to the car stereo is using a cheap ($10) cassette adapter, because the car player is a CD/Cassette/FM player. With that, its easy and there is no audible sound loss. If you do not have the outdated cassette player, then FM modulator will work, if you have a lot of patience and don't mind lots of hissing and static. The aux out as mentioned by Sean is the best option in that case.