So I was looking at my old system results that ran a Athlon 64 x2 6000+. I ran it on my phenom II x4 965 BE (C3) and got 10623 points with a cpu score of 11529. My old Athlon got 11535 with a cpu score of 26493. I'm assuming that there was an update to it since the athlon years?
You need to make sure you are running the same version of 3D Mark with the same settings. You likely ran an older version of 3D mark on the Athlon system as 3D Mark vantage requires direct X 10 to run which mean it needs windows Vista or windows 7 and a DX 10 capable graphics card which an old Athlon system likely does not have.