I've found myself using the "Septuagint Version of the Old Testament" when comparing Septuagint and MT readings; but it would be great to have an English translation of the Septuagint that isn't 166 years old [:)]
This fairly new translation published by Oxford looks good:
http://ccat.sas.upenn.edu/nets/
You can even download it in PDF form from their website so shouldn't be too complicated to produce right? [;)]