I'm going to build a PC for my wife and kids. I'd like to get some advice on what components are best, whether I should maybe just get one out of the box, or even go with a laptop.

1) I'd like to spend fewer than $400 (I don't need a monitor)

2) It should be able to play games for my kids but it doesn't need to play Modern Warfare.

3) It needs to be powerful enough to play video files.

4) Obviously, internet and word processing are important.

5) Saving $ is key; that's why I think building it myself is best, but I'd gladly save myself the trouble and get something out of the box if the cost difference isn't too much.

I'm experienced in builds, but it's been over a year and a half since I built my own rig so I'm pretty uncertain where things have gone since then.

Thanks very much!