Samsung vs. LG HDTV (w/ Xbox 360)

I've done some research and still would like some quick help, as I need to make a decision today. I was going to post this in the Samsung area, but I'd like as unbiased an answer as possible (if that's possible!).

I originally bought a Samsung 40 inch HDTV that I returned the following day because it was just too big and was making me and my fiance motion sick! I ended up returning it for an LG 37LH30 due to the price being the same. I was considering the Samsung LN37B550, but it was $100 more and at the time I wasn't sure that I wanted to spend the extra money.

I've had the tv for almost a month now, and for the most part it's great! I really love it. However, there are a couple issues that I've noticed and I'm not sure if it's the tv or not.

These issues only occur when using our Xbox 360. When we play Lego Indiana Jones, there seems to be a bit of a "lag" when running a character across the screen. In Madden 2009, there is also this "lag" at various times within the game. I have output resolution on the 360 set to 720p because I was having issues at 1080p (certain games or scenes would seem to flicker or black out). Now, after reading some reviews, I'm wondering if the Samsung would be the better option and would look "smoother" when playing certain games. I can exchange the tv's (would have to be tonight) and then have 30 days to try the Samsung to see if I like it. The extra money is not a concern at this point either.

When I chose the LG, the store employees were saying that they had LG's that they loved. They said would have bought the Samsung though if they had the extra money to spend.

Any input on this would be greatly appreciated!

Thanks!