Should I trust these companies?

So, I posted an ad on craigslist looking for a job and had 2 potential responses. One claimed to work for AE Media Group located in Duncanville, TX and the another for PFS Investments Inc. located in Arlington, TX. I sent both my resume..and both responded pretty fast, by calling me and saying they wanted to set up an interview. Should I be worred? I'm iffy on calling them back. Any suggestions? or information regarding these companies?