Take my response with a grain of salt ... I'm not an expert on computers
I own a Dell Inspiron (old) ... mine also has the same card (Sigma Tel); if I understand correctly the microphone input can be considered a line in input (I don't think they wrong here) ... check your computer, and see how many connections you have on the sound card (mine has two; one for microphone and the other for the headphone); if this is the case ... I'm sure is better to get an external card because in reality you only have the microphone not a line in need it for REW ... (I got the Soundblaster Live 24Bit, it costed me $50 at Circuit City)
Hope this helps ...
