Well, if Rita does explode into a hurricane once it reaches the Gulf and tracks towards Galveston, that'll be the first time since Hurricane Alicia in 1984. These things come in cycles, and I do hope that locals there haven't been lulled into complacency from the time span.
I was raised outside of Angleton, and have visited Galveston many times. The massive seawall will serve well, but beach erosion will be massive. Possibly not, come to think of it. There's many sandbars about 100 feet or so off the Texan coast, especially around Freeport, and those will be pushed inland as the waves pound and erode the shore. Not to mention the continental shelf off of Texas extends several hundreds of miles into the Gulf, drastically shallower than the depths off the shelf. Still, won't hurt to be well stocked, and be sure to stockpile water. In a pinch, a freshly scrubbed and decontaminated bathtub works wonders.
In fact, I'll be in Angleton by Friday. Fun fun, if Rita heads west.