Answer to "No Sound from Mac Mini!"I had the same problem with a Core Solo machine. Turns out the people who installed some RAM (this was before I discovered ifixit) had not properly seated the ZIF cable in its socket. Steps 7 and 8 in the Audio Board install (Mac mini Model A1176 Audio Board Replacement) are where the solution lies. There is a painted line on the ZIF cable. Before you close the cable lock, make sure the cable is fully inserted - the painted line will be about 1mm above and parallel to the top of the socket. Push down the clip and all should be well.
Answer to "Can my 1.5Ghz SoloCore be upgraded to a DualCore processor?"I upgraded a Core Solo 1.5GHz with a T7600 Core 2 Duo 2.33 GHz. The guide here on ifixit is well done, and along with the notes on each step, it was all I needed to do the work. I would say having the proper tools helps a lot. Who knew a spudger was so important :) Gary O'Brien Photographer Charlotte, NC
Answer to "Mac CPU upgrade speed?"I also just installed a T7600 2.33 GHz, and it was pretty much by the book. Read all the notes in each step before you do the step - they are a big help. Also upgraded RAM and HD. The little machine is stepping along quite nicely now. Gary O'Brien Photographer Charlotte, NC