Could you download the following file
http://www.dell.com/support/drivers/us/en/19/DriverDetails/Product/inspiron-1720?driverId=XV8FK&fileid=27311000441.Double-click the new icon on the desktop
2.The Self-Extracting window appears and prompts you to extract or unzip to "C:\DELL\DRIVERS\Rxxxxx". (Where 'Rxxxx' is the name of the file to be downloaded). Write down this path so the executable (I.e.Setup.exe) file can be found later.
3. The Self-Extractor window appears.
4. Click OK.
5. After completing the file extraction, if the Self-Extractor window is still open, close it.
6. Copy the entire folder to a USB drive
7. Reboot to the reatogo desktop
8. Insert the USB and copy the folder to the root C:\ drive
9. Go to "C:\DELL\DRIVERS\Rxxxxx" (where 'Rxxxx" is the name of the file) in the Open textbox and then click OK.
10. Follow the on-screen installation instructions.