A lot of big tech and wireless companies in Dallas (Verizon, Texas Instruments, IBM, etc). Some noteworthy game companies are located in Dallas too. I would say Austin has a better investment climate for startups than Dallas, but thats not to say there are not any good startups in Dallas too.

The problem I see with Dallas is the personality of the city is a bit bureaucratic. At least relative to other startup hubs such as SV, Austin, and Seattle, which seem to have more of an outdoor-loving hippie vibe.

Dallas is sufficiently "young" though. Lots of new young talent coming in. I believe Dallas is actually one of the fastest growing cities in the US right now.