Westinghouse is a decent budget set. I have one now (37") and it's a good set. I plan to take it back however, because I figured if I'm gonna spend so much money, I might as well spend a bit more and try to get the best set possible.
I don't know if you've had an LCD set before, but there is slight image blur with fast moving scenes (like in sports), and in games. I set up a shooting game to see how it worked on the Westinghouse, and is super-blurry when swinging around to target different stuff. Again, maybe this doesn't affect some people, but it was enough to make me take the set back. I think even higher-end models have a slight problem with this, I guess it's just a limitation of the technology right now.
I would check out the sets to make sure the blur effect isn't too bad, and then purchase one. Again, the Westinghouse has been fine outside of that. The only experience I have with a Vizio is with a very large one that I have at my work (50"?), and it's ok. It seems to accentuate red tones, but again, maybe the people didn't adjust the settings correctly. Maybe it's comparing apples and oranges, but the 37" Westinghouse seemed to have better picture quality, while the 50ish" Vizio seemed to be better at reducing the blur effect. But again, they are completely different sizes so I'm not sure you can really compare them.
So again, even though I'm taking my Westinghouse back, I would recommend it for budget shoppers. It's not perfect, but it's a good set given the prices you can probably get it at.