I guess if you were really on the cheap, you could shave $20 off and stick with 2gb of RAM. But DDR2 is practically being given away. I wouldn't buy a copy of Windows off of Ebay even if my life depended on it. You're really not going to find 'deals' as every place is going to sell a legit full copy for the same price, or roughly.
Other than that 400W Rosewill PSU that's going to be mostly garbage, that system is fine. Cheap PSU's are always a gamble. I just got a computer off of Craigslist for free that a guy couldn't fix or didn't want to. His Okia brand PSU (which was feather weight light) fried his motherboard, CPU, and RAM. It came with a nice burnt smell with it. I salvaged what I could.