Why did my computer download NVIDIA GeForce?

It automatically downloaded this software it said it was important! It has changed a lot of things on my computer on my desktop and in certain programs it even changed my fonts in all programs. I do not want it and want to know if I can delete it w/o causing any problems. I tried to call Microsoft and could not speak to anyone that wasn't a foreigner and could not understand them so I gave up on that. I asked if there was someone there that could speak English or was from United States. Hmmmm very frustrated.