AHCI mode makes a huge difference, you're fortunate to get what you have now without it. The 4K scores are very dependent on AHCI mode, particularly in benchmarks. I don't understand why one benchmark would be better in IDE mode.
It looks like you are barely in SATA III performance territory, if at all. Does that PC support SATA III?
parsec - thanks for your reply.
Yes, it is unfortunate - I guess I should have done my homework a bit more. The 2011 MacMini does support SATA III but mine shipped with a SATA II 5400 Drive.
Even in IDE mode, the performance is without a doubt much better but I had hoped to run VMware Workstation on the Windows side with a VSA (Virtual Storage Appliance) and nested ESXi's for testing and studying.
I'll test around on the Mac OS X side and see if I can my hands on a more reliable disk bench marking tool and post my results.