How about a column chart. The area chart overemphasizes some points more than the values should allow. Since the points are discrete measurements, the sloping lines between measurements are meaningless, and displaying filled areas is going to be misleading.

**Method 1:**

Plot column chart. Set vertical axis so horizontal axis crosses at value of 2.8 (or whatever). Format column fill: check Invert if Negative, and select the two colors for positive and negative (which works in 2010, but 2007 is a disaster for setting these colors). Set gap width to whatever looks good; default is 150%, but I used 50%.

**Method 2:**

Easier, no problems with Invert if Negative.
Use formulas in two columns to produce a series for up and one for down. I put the dividing value (2.8) into cell B15. Formulas for column C (up) and D (down) are:

```
C3: =IF(B2>$B$15,B2,$B$15)
D3: =IF(B2<$B$15,B2,$B$15)
```

Select A1:A13, hold Ctrl while selecting C1:D13, and insert clustered column chart. Set vertical axis so horizontal axis crosses at value of 2.8 (or whatever). Format the two series as desired, and use an Overlap of 100%. Set gap width to whatever looks good; default is 150%, but I used 50%.