theres probably a trillion different variables that affect the time to complete a WU (number of frames, cpu speed, how much your using your pc, type of WU, etc)
heres a little tool i found to see if your getting the frame times u think u should be getting
The main machine I use to fold is somewhat similar to yours (ill post specs below) and it takes me about a day or two on and off to finish a WU. I only fold with it when lookin on the forums,net,talking to people,dling music,sleeping,not home,etc. So it folds a total of maybe 12 hours a day. Heres the specs.