Hello d_say.. Well your letter is good.
But its too short for the other Firm to get to know about your company.
Your Intro Letter should have all the information about your company right from its status in share market, profit and loss ratio of the last decade, etc..
Your Intro Letter should be such that the other party can get to know about your company in one Snap Shot..
So give some more information.
And last line should be
"We are looking forward in doing business together in future with you"
Thats all I can suggest d_say...