I'm looking for for a driver for i-river MP3

IFP-790 can be accessed in UMS and Manager mode:

UMS mode
For firmware upgrades iriver PLUS3 must be used.
Download iriver PLUS3 going to this site:
http://www.iriver.com/index.asp
Click Support on the left side.
Select Download in the second column.
Select "Download iriver PLUS3" in the page: allow download (when blocked / sometimes download has to be repeated).

The size of the iriver PLUS3 download is 59.3 MB.
iriver PLUS3 can also be used for music transfers in UMS mode.


Manager mode
For Manager type connection the iriver music manager must be downloaded and installed.

Go to the support site:
http://www.iriver.com/index.asp

Select Support in the first column.
Download in the second column.
Enter the phrase 'music manager' and click GO:
download 'iriver music manager (Ver 3.21)' [ 28 MB].