alekth on 15 May 2010
Yes, there's stuff like that http://www.google.com/products/catalog?hl=en&rlz=&q=usb+ethernet&um=1&ie=UTF-8&cid=3909049789702220635&ei=AN3uS8SIC8_8OertyIAJ&sa=X&oi=product_catalog_result&ct=result&resnum=4&ved=0CDAQ8wIwAw#
That was just a random google pick, haven't reserached any reviews. But since it's a desktop, you can also put in an ethernet card unless all the PCI slots are already occupied.
Also check in the Device Manager whether it finds the ethernet port and reports a working driver.
