Yes, it is possible to add a hyperlink to only a couple of words in a sentence or paragraph in a cell in Excel 2007. Here are the steps to do so:

1. Select the cell that contains the text you want to add a hyperlink to.
2. Highlight the words you want to add the hyperlink to (in this case, "test.doc").
3. Right-click on the highlighted words and select "Hyperlink" from the drop-down menu.
4. In the "Insert Hyperlink" dialog box, select "Existing File or Web Page" from the options on the left.
5. Browse to the location of the file you want to link to and select it.
6. Click "OK" to close the dialog box and add the hyperlink to the selected words.

Now, when you click on the words "test.doc" in the cell, it will open the file you linked to. The rest of the sentence will remain unchanged.