Hi,
The terms "jutsu" and "jitsu" are different words, different kanji, and have different meanings. "Jutsu" has a translation in most Kanji dictionaries I have read of "practical art", whereas "jitsu" is translated as "truth", or "real" (sorry, my computer doesn't like me trying to post the kanji themselves...), and is never used to describe a Japanese artform - in fact, the only readily acceptable use of this mis-spelling is Brazilian JiuJitsu, which has been moving away from it's Japanese roots since Maeda first taught the Gracies and Machados nearly a century ago. Oh, and for the record, I am refering to the Kodansha Kanji Learners Dictionary, edited by Jack Halpern for my reference if you want to check them out yourself.
The site refered to by Tsuki Yomi seems to be more of a "well, we don't mind how you say it" kind of approach, rather than an in depth look at the language, but if you want to check it out, try to find a copy of Tanemura Sensei's old Panther Jujutsu series, number 6 (History and Traditions), where he illustrates in no uncertain terms the fact that the words are pronounced JU JUtsu, not JIU JUtsu, JU JItsu, or any other combination. He shows the different characters, and explains the different meanings pretty well there.
And while I'm here, yes, everyone is certainly welcome to post in any area, regardless of experience, in fact, that is one of the bes aspects of this particular forum... however, this thread is Ninjutsu-specific. If it was in the General Martial Art section, then an open discussion of different arts and practitioners approaches would be wonderful. But it's not, so I don't think it's unreasonable that if the question posed is "Areas of Special Importance In Your Training (In Ninjutsu as per the forum section)" that the answers be based on training areas for ninjutsu training by people training in ninjutsu. If someone not training in ninjutsu wanted to see what practitioners do focus on, great... but they would not be qualified to say what their focus in ninjutsu was. Make sense?