To Change IE9 and IE10 Default "Save" Download Location in the Registry do the following:
1. Press the Windows + R keys to open the Run dialog, type regedit, and press Enter.
2. If prompted by UAC, then click/tap on Yes (Windows 7/8) or Continue (Vista).
3. In regedit, navigate to the location below.
4. In the right pane of Main, double click/tap on Default Download Directory to modify it.
5. Type in the full path of the folder that you want IE9 or IE10 to save downloads to by default, and click/tap on OK.
6. Close regedit.