The Def Tech Pro 100s will give decent performance in a smaller room but in an 18x20 they will be inadequate. Speaker that size may be acceptable for movie viewing if you have so so expectations but try some budget small bookshelf speakers from B&W, KEF, Monitor, Jamo, NHT, PSB, etc. doe 350/pr + a $250-300 center channel plus cheaper surrounds and you will experience a sectacular improvement over any sub/sat system. With some tough negotiating you could pull it off for 1K. All of these sub/sat systems are limited in their ability to move air and you will notice it especially listening to music. Bang for the buck, go with the Jamo's and you could include a sub for under a grand.