Eva, I see that your query was moved to this existing thread. Check out the earlier posts since there is good information there. Definitely check out Derrick Riches reviews at
http://bbq.about.com/cs/grills/bb/aabyb042503.htm.
Here are a few additional thoughts:
1. This is a good time of year to buy a grill since I think there is a lot of discounting. Check out Abt, as well as your local Home Depot, Ace, True Value, etc. for sales.
2. I really like the cast iron grates on my BBQ Grillware (a Lowe's brand). They are heavy and retain heat very well.
3. Try to get a grill with at least three heating elements. Three "zones" makes it easier to cook over indirect heat. The smaller, cheaper grills only have two zones. Many, including mine, have three zones going side to side. Some have three zones from front to back. I happen to like the side-to-side set up.
4. Weber is the "king" of gas grills. They are easy to find. The cheaper Webers don't have quite the reputation as the mid and high-level ones. There are plenty of good brands out there, so don't get so stuck on one.