More advice on gaming rig

looking to build a budget gaming rig and already purchased some parts, looking for some suggestions and advice to my next steps. first time building a pc, please go easy [:

have

cpu - intel celeron e3200 (looking to oc to ~3ghz)
http://www.newegg.com/Product/Pro...-_-Product

mobo - msi g317m-p21
http://www.newegg.com/Product/Pro...-_-Product

ram - 2-2gb of ddr2 pc2-6400, 800mhz, 5-5-5-12
http://www.newegg.com/Product/Pro...-_-Product

hd - 1tb

only looking for a gpu now. wondering how should i go about this, is everything going okay? another question is saw specs for my mobo and i realized the pci-e x16 slot isnt 2.0, is that going to be a problem when purchasing a gpu that utilizes a 2.0 slot? thanks