I found that my idea to put in a PCI serial board into my old vista HP computer was right on, however.. when I actually removed the case, I found that the promising PCI slots were dummy covers and there were no PCI slot available in the unit.
SO I need to find the right USB-to-Serial (DB9) Cable that is compatible with the weatherlink serial logger. I see a number out there, and Davis offers one for $26US shipped. but still if i can get it a little less, with a vista compatible driver.. is there such a beast?