I had an XPS 8100 and you will want a smallish PSU. It doesn't need to be tiny, but I would recommend a ~550w PSU slightly smaller than a Rosewill HIVE 550w. Also watch the GPU length. The HDD cage got in the way on mine.
Im thinking EVGA GeForce GTX760 SuperClocked or EVGA Geforce GTX660 for the GPU cant decided if i want to spend the extra 50$ I mostly play MMO's