PCI upgrade?

So my computer (Dell Dimension E510) has a PCI-E 1.0 port, and I want to upgrade my video card. The card I am looking at needs a PCI-E 2.0 port to work.

Can I upgrade the port or do I need a new motherboard/computer? If I can upgrade it, how hard/costly would it be?

You can't upgrade the port. Also you can run a PCI Express 2.0 card in a PCI Express 1.0 port you just won't get the full capability out of the card. Your next hurdle will be the power supply and power requirements of the new video card.