That cable would have been ideal for connecting to MIC IN as it will come straight from the cartridge unfortunately as you have a built in MIC you probably wont have another input into your on board sound.I think the best way would be for you to get a PCI soundcard,(unless you want digital 5.1 surround etc),a cheap one should do for only a few pounds.Then you would just need to install it and disable the onboard sound in Bios and use the MIC IN on the PCI card.
Just a thought though Lona,my deck has to go through a pre amp before it connects to my AUX IN on my mini Hi Fi,your deck hasnt got a built in pre amp as far as you know does it?