Being unable to contact the Microsoft site, or other websites, is sometimes the symptom of a virus or Trojan somewhere in your system. One free antivirus program I've been happy with in the past (and I'm sure your other friends can also suggest good ones), is Avast Antivirus. It doesn't hog system resources so badly as other programs, and once installed it allows you to reboot the machine and perform a virus scan in the boot process, before Windows loads and the viruses become active.

It's hard to say what would cause the keyboard sensitivity; it could be corrupt or incorrect drivers, or even dirt particles caught under the keys or the keyboard assembly, where the electronic contacts are.

It might be worth the time to search around the Dell Support website and look up your model number, to see if there are any known issues with your model, or if others have posted relevant support topics about it.

In the past, I've also learned a lot simply by plugging the model name and a relevant keyword (eg, keyboard problem or low memory) into Google. This can lead you to support forums, where people may be discussing the very problems you're encountering.

Hope any of this helps, and best of luck to you!