Hi Brian,
Here's one workaround -although it won't be in the header area itself. Paste the picture in the first few rows of cells at the top of Sheet 1. Then in File | Page Setup | Layout tab, click in the box "Rows to Repeat at Top". Select the rows in your worksheet that contain the picture by selecting the row numbers themselves. You'll see a range appear in the box you clicked in. These rows will now appear at the top of each page, like a header.
Good luck,
BlueHorizon