Depending on the age of your TV you may receive complete 5.1 from the TV as well as all connected components. On newer TV's, since 2005 I think, any native content from the TV, OTA or cable without converter box, will output the full 5.1 signal if available. All components connected to the TV via HDMI will output only dolby digital stereo. This is a DRM issue that all TV manufacturers selling in the US have consented to, not a problem with the TV.
If your TV does not have HDMI, then perhaps one of the Sony units or the Yamaha would best suit your needs.
Also, as far as the receiver goes, any decent receiver is going to more than double your initial outlay amount. If you go with an inexpensive receiver, you will probably end up with about the same quality electroics, maybe worse, than those included with the soundbar.