buckworks - 8:59 pm on Aug 11, 2011 (gmt 0)
Use both: inquiry here, enquiry there. Love everyone.
That does not solve the conundrum; it only delivers a different sort of irritation.
Unless you are discussing a topic that actually requires the nuances of meaning that reach back into history, choose one form or the other and be consistent about it.
A quality publication will decide on their house style and stick to it.