Hi Will,
From what I can tell that desktop uses a standard ATX Power Supply. You might want to quickly measure the dimensions first though. It should be 150mm x 140mm x 86mm.
If you can take some pictures of the power supply, it would help. Sony does not have any record of using any proprietary power supplies in their desktops, so you should be all set. Take a look at these:
http://www.newegg.com/Product/Produc...82E16817371002
http://www.newegg.com/Product/Produc...82E16817371001