There is a nice interview of Peter Gentry concerning the Septuagint. I have reproduced part of the interview below. For the rest go here.
Should it bother evangelicals who believe in the inerrancy of Scripture that the NT writers sometimes quote the LXX where it differs from the Masoretic text?
The NT writers sometimes took the Septuagint wording and applied it to a new circumstance (e.g., Acts 14:11 borrowed words from Ps. 118:22; 2 Cor. 16:8a borrowed words from 2 Sam. 7:14 and other texts). At other times the NT writers corrected the Septuagint reading in order to bring it into greater conformity to the Hebrew texts (e.g., see the use of Isa. 28:11–12 in 1 Cor. 14:21, or the use of Isa. 63:10 in Eph. 4:30). The use of the Septuagint doesn’t imply that the NT writers thought that the original Hebrew was mistaken; rather, it means that they affirmed the truthfulness of that which they were quoting or adapting in their own writing.
Why is it important to study the Septuagint?Several reasons make study of the Septuagint important: (1) It provides extremely early textual testimony to the Hebrew Scriptures; (2) it provides us with an extremely early understanding of Hebrew grammar and word meanings otherwise unknown to us; (3) it essentially provides for us the earliest commentary on the Hebrew text (since all translation involves interpretation); (4) it serves as a key witness to the thought and worldview of Second Temple Judaism (c. 450 b.c.–a.d.70), since it was produced in the intertestamental period; (5) it is the key to understanding the Greek of the NT, since it was used so often by the apostles and by the early church; (6) it can shed light on translation debates today.