I just released a minor update to Stirling Weather Tray. Version 1.2.2599 adds a color scheme option for the taskbar icon. The two options are: "Normal," which matches the scheme from previous versions, and "Light" which uses white instead of black and a light blue and light red for the cold and hot temperatures respectively. The new color scheme should improve compatibility with Windows Vista's Aero UI and also with the Windows XP blue scheme.
All existing installations should be automatically updated the next time Stirling Weather launches. Otherwis, you can install the update from my Windows Software page.