http://support.dell.com

I looked and I see that Dell does not have Windows 7 drivers for the Inspiron 1420.

You might try downloading Intel's chipset drivers for the Intel 965 that supports Windows 7.

Welcome to the forums

By all means follow the advice offered by Bay Wolf, but the "base system device driver" is usually the media card reader - specifically

And drivers for the media card reader are not included with the chipset drivers. They have to be downloaded/installed separately.  

If it's a 32bit version of Windows 7 HP you've installed, the Vista 32bit drivers provided by Dell *might* work?

If it's a 64bit version of Windows 7 - or the Vista 32bit drivers don't work - then you'll just have to try and source suitable drivers elsewhere I'm afraid.

That's the chance you take if/when you decide to upgrade to Windows 7, and Dell don't provide Windows 7 drivers.