Welcome to Texas!
I lived in that part of town for about 7 years and work there currently, and its pretty desolate. Lone Star Comics has a store up in Plano, and there is a local card shop at Arapaho and Jupiter that carriers some RPG materials, but most of the best stores are located outside of the area. My best picks would be:
Lone Star Comics flagship store in central Arlington - this is the mothership to our local chain of "speciality stores" and carries a wider selection than their other locales. They try to hit too many interests for my tastes, so their RPG selection isn't as good as others. But if you want a store with a "good enough" selection of comics AND anime AND japanese toys AND Warhammer AND other stuff, this is a one-stop shop. It has its own gaming room.
GenerationX Comics in Bedford - this store is about as centrally located in the entire DFW metroplex, and is about five miles to the west of the DFW International Airport. They carry almost all new game lines that come out for both RPGs and miniatures, and has a good selection of games that have gone out of print. This is the best store to find something (RPG/mini/boardgame) just about everytime you go. They also carry comics and graphic novels, but don't have the japanese games and gee-gaws LSC carry. Gaming room on site.
Game Chest in Valley View Mall (North Central Dallas) - if you want to stay in the area of RIchardson, this is probably the best well-stocked game store you'll find. While their emphasis is on board and card games, they carry a really good selection of RPGs. They don't carry all the mini lines from Rackham and GDW, but they have DDMs and Heroclix. No gaming area available.
Area 51 in Grapevine - a new store that opened west of the Airport, while their selection is just starting out, they have a great staff and are carrying some games I'm not seeing elsewhere like Field of Glory minis and Flintloque. So-so with RPGs though, they are only carrying news stuff. Three large gaming tables and a separate room.
There are other good stores around, like Y2K over in Fort Worth, but that would be a haul for you.
This area of town also has a good gaming community. You'll want to check out penandpapergames.com to get connected.
Good luck when you get here!