Sorry to butt in here, but I think I can save you some time.
TadawulFX (TDFX) does not deal with U.S. residents. Here is a quote from a recent TDFX communication:
Due to the regulatory restrictions in the U.S., it is with great regret we inform you that Tadawul FX will no longer be able to accept any transactions from U.S. residents from 8th July 2011.
For the full text of that communication, click on this Babypips post, where it was originally posted:
If you are not familiar with the thread titled "Going offshore to escape the CFTC", you should check it out. Initially, you can skip trying to read the whole thread --- it is very long. Instead, go to the lists we have compiled of offshore brokers who will, or will not, do business with U.S. residents.
Currently, the 3-page List can be found at Post #944, Post #945, and Post #946. Periodically, as the thread continues to grow, I move the List to the end of the thread, so those post numbers are subject to change from time to time.
10/9/11 Edit: Currently, the List can be found at Post #1072, #1073 and #1074