Please help with graphics card upgrade, Dell Inspirion 560.

I am trying to upgrade my PC to play Guild Wars 2. I should also state upgrading components is a new venture for me, so any other elements I forgot to include can be if necessary.

I have a Dell Inspirion 560 with dual core CPU e5800 @3.20GHz, 3.00 GB ram. I purchased an Antec BP550 Plus 550W Continuous Power ATX12V V2.2 80 PLUS Certified Modular Active PFC Power Supply that I plan to attach to my PC. I also purchased an ASUS GT630-2GD3 GeForce GT 630 2GB 128-bit DDR3 PCI Express 2.0 x16 HDCP Ready Video Card.

My problem is that after scanning through many threads after my purchase, I found some stating I need a low profile card for my system. I am also unsure on the specific type of card I should get, DDR3, PCI 2, all of these specifications seem to confuse me as I cannot find a list that states your computer simply needs this specific type of part anywhere?

Can anybody tell me a few recommendations for a new Graphics card in order to play Guild Wars 2 on my PC?
I am willing to spend up to $100 on the GPU itself.

Any help would be greatly appreciated.