Microsoft Excel 2007 allow users to add comments. If you want to change the comment colour in Excel 2007 to your preferred choice then you can follow the following steps
1. Right click on the Desktop properties and select Personalize option
2. In the Personalization window, click on the Window colour and Appearance link.
3. Click on the Open classic appearance properties for more colour options link
4. Click on the Advanced button in the Appearance Settings dialog box
5. This would display the Advanced Appearance dialog box, where you can select ToolTip from Item drop down and select colour your choice for the comment.
Using the above steps you can change the colour of comment in Excel 2007.