I currently have a Pentium D 915 which I bought almost 2 years ago. I haven't actually thought of upgrading the CPU until now but my the best processors my motherboard can support are the Core 2 Duo E6x00 range. Link to my motherboard.
Do you think that it's worth AU$86 to upgrade to the Core 2 Duo E6300?
Also, are there any benchmarks on this kind of thing?