i like sean w.'s parts reccomendations, should go with that. On a personal note, i would go with an nvidia card, but thats my bias talking, to each his own. Really doesnt matter in the end.
Make sure you assemble your computer on a wooden table or the like hard surface, carpet can cause static electricity which is no bueno for parts.
idk bout easier then legos....but most definitely easier then anything unassembled from walmart. They make it look so simple on the box, little do i know the next two hours are filled with missing screws, wrong parts, parts that dont fit....instructions that make no sense and might be in wrong language, headaches, beer drinking, then light on fire......I just wanted a computer desk walmart.