Vostro 420 & Windows 7

I bought a Vostro 420 pre-installed with Vista Business in September.  All OK until I installed Windows 7 Professional using the Dell Upgrade kit.  To start with picture on the monitor did not occupy the entire widescreen, it was only 4:3 so I contacted Dell Hardware Warranty Support who resolved this issue - but gave me another one!  My previously quiet system now has a loud hum - I was a bit concerned about this so contacted the Support Chat again who suggested I start taking it to bits to isolate the problem.  I wasn't keen to do this so they suggested installing various drivers who may solve the problem and run a diagnostic Express Test which showed up three other problems.  Went back to Hardware Chat with the results of the test - and also another problem - my 19-in-1 Media Card Reader is now not available!  More drivers were installed by Dell - still now success and it also seems that the 19-in-1 Media Card Reader is not compatible with Windows 7!  I apparently have to wait till Dell writes a suitable driver to correct the problem.  Am I alone or does anyone else have these problems?