Get x540. Trust me. There are 4 satellite speakers, 1 center speaker, and 1 Sub. You can mount the 4 satellite speakers on the walls, the center you could put on your monitor (or anywhere around you) and the Sub should go on the floor. Make sure the Sub is positioned the way it should be. Oh YEAH! Get this off eBay. Here are some good ones, and they're under $80.
http://cgi.ebay.com/Logitech-X-540-X...QQcmdZViewItem