I'm not sure what issues you are having, but my copies of Excel 2007 and 2010 both allow you to insert another Excel sheet as an object. To do it, you need to click on the Insert tab in the ribbon, and then click Object. This will open a dialog window allowing you to set the object to insert. Click on the Create from file tab to insert your specific file. Click browse and select the file you are looking to insert.
There are a few checkboxes for options. Link to file will put a reference to the file, so any edits made to the embedded workbook will be reflected on the original. Display as icon will show an Excel icon with the name and location of the original file. Leaving this unchecked will embed the sheet itself within a floating, moveable and sizable window.