Upgrading Graphics card information

Hello I have a Dell Inspiron 620 with the i3 2nd gen. I'm looking to upgrade to a better graphics and bigger PSU. The card I was looking at is http://www.newegg.com/Product/Product.aspx?Item=N82E16814150561  But I was reading that there might be issues with the card being a pci e 2.1? Now how do I find out if the motherboard is able to support pci e 2.1? I've been trying to find out which motherboard the Inspiron have, but have been coming up short. Maybe I haven't looked hard enough, but any help would be greatly appreciated. Also which PSU would fit in the 620?

I would not worry about that, all cards are backward compatable. So a PCI 2.1 will work in your system, and you will need a ATX type PSU to run that card, I use the Corsair CX 600w v2 in my 570, with no problems.

There will be no Issues with PCIE 2.1 and the card.

You need a certified power supply.  AMD Radeon™ HD 6850 uses 2X   6-pin PCIe power connectors.

Certified power supplies are recommended.  Refer to http://ati.amd.com/certifiedPSU for a list of Certified products.