If you are using mobiles of these companies and are not using their PC suites. You are missing a lot.
Both these companies offer nice programs to sync your contacts, music, pictures and videos. They also allow you to convert the videos so they can be played on your mobile.
Nokia PC suite
I like the nokia PC suite because it detects the phone automatically and also display the picture of the phone. So you can be sure it has detected your particular phone. It pops the nokia PC suite in a small window with all the shortcuts.
Once you click a particular shortcut a window opens up with the app.
Like address book which will let you import contacts or back them up etc.
Similar all the multimedia have programs where you can import, edit and convert them.
So download the nokia pc suite if you have a nokia phone its around 25 Mb. You can find the nokia pc suite here.
Samsung kies software
It opens up a big window with all the apps loaded in smaller windows. It too detects your phone automatically but doesn't show the exact image of the phone which can be a bit confusing.
Its a lot more customizable than the nokia pc suite. It too offer all the feature like importing photos, contacts and videos etc.
You can also copy files, photos, music and videos to the phone from the pc suite.
So download the samsung pc suite if you have a samsung phone its around 120 Mb. You can find the samsung kies software here.