I have a similar problem and I have found the best that can be done, if you know a second language, is to translate a paragraph at the time and edit the original paragraph until the translation is acceptable.
I have done that with an original text in English translated to French and the result is good.
The remaining problem is that the translator tries to translate names and surnames and some words are translated differently according to the context, for example "moderator" is sometimes translated correctly and sometimes translated as "president"
I have used the Google translator which is fast, free and free of commercials (have to log in as another user to find the link).
I have tried a commercial software subscription that was looking reasonably priced but it is a word for word translation.
I have tried other free translators and the results are the same. I could not find any commercial software that cost less than about $1,000 per year per language.
At the moment I assume that if the original is edited suitably, the translator will give the same quality of translation in other languages but this may not be correct. I will post examples of translation in another thread.
So far I have translated about 200K of plain text with the only purpose to see what result people get when they translate the original into their language.
The main difficulty seem to be words that can have different meanings. From what I have read, we will not get much improvement in free translators for a long time.
Hope this helps.
http://translate.google.com/translate_t