Here's a build that is just over your $400 budget...about $430 at time of the build. Personally, I would upsize the HDD to a 1TB 7200rpm Seagate Barracuda for another $10. Assembly/testing fee is extra (up to $50...or PM $25 at Infonec). Monitor, keyboard and mouse are extra. You could save $12 by going with a Celeron G530.