Can someone help me?

Can anyone build me a decent gaming pc for under $400?

I'm new to this.
I want to gain experience but don't want to spend a lot right now.
It doesn't have to be great, I don't expect it to.
However, I want to be able to run games such as combat arms, or any mmo.
Would also be nice to run skyrim, diablo 3, ect.

I only have $400 to spend right now.
Like I said, I'm only looking for experience in building right now, I'll eventually build a higher end pc.

I have a monitor and windows 7, so that isn't an issue.
However, I don't have a keyboard or mouse (writing from laptop)

If anyone could help me with this, It would be greatly appreciated.

Also, I'd like to stick to newegg if at all possible.

Thanks!