Heres a link to the Dallas TX electrical requirements:
http://www.dallascityhall.com/buildi...l_section.html
Around here depending what City/County your in, we work under NEC 1999 thru NEC 2008 and of course your always subject to the whim of the local AHJ inspector.
I have to agree with Ron on the fact that the electrical needs of modern household far out way what was needed in the 50's. A full rewire may be worth the cost.
Make sure you get everything in writing in the estimate, DONT ASSUME ANYTHING NOT IN THE BID IS INCLUDED! Also nail down a hourly rate and material markup for any extras before you sign a contract, last thing you need is the extras costing more than the bid job. Be detailed in telling the contractors what you want and get no less than 3 bids. Let each contractor know several people will be bidding on the job, makes them sharpen the pencil a little more. Right now construction work is slow, and contractors are taking work at cost and below to keep there men busy.
Congrats and Good Luck.
Allen