Ditto on the Barnet Ghost 400. I would suggest however that you shoot it or some other similar crossbow at a range before spending your money on a crossbow altogether. Cocking one is time consuming and can require considerable strength or additional equipment (they make it look real easy on TV). They also often weigh more and are more cumbersome to handle than most people expect. I know a few guys that have bought crossbows, shot them a couple dozen times and put them in the back of the closet.I would HIGHLY HIGHLY recommend the Barrnett Ghost 400.
While I own one and am glad I do, I would do not consider it a substitute for a good medium game rifle or shotgun. They're pretty much a one shot defense weapon. If you miss on the first shot, an aggressive opponent could easily over run you from 50 yards away before you could load another bolt.
They're a great sporting bow for deer though (after you're trained and licensed) and make a serviceable second choice for hunting if a firearm isn't available or practical. That said, you might find a compound bow more desirable, but be ready to put some time into practice.