Thanks for your reply, lifeking. Interesting. I noticed that recommendation/article mentions that processor's advantage in gaming. But, this is going to be a non-gaming PC, so would you still recommend paying $45 more to buy the i3?
PepcapsL - I think you are right. The article (recommendation) is focused on gaming. Here is a quote from another article and it includes the AMD processors you are considering so it may shed some light on the subject.
"The worst thing we can say about it (i3) is that its dual-core Hyper-Threaded architecture might not perform ideally in parallel tasks, but that doesn’t seem to slow it down when it comes to gaming."
So, pencapsL, the combination of the above components replacing their couterparts in Lifeking's build allow you to get the most out of a $400 budget. As for your question about an i3-2100 vs. an Athlon II 455, the i3 beats the 455 in all but one test, where it loses by 1.2%. It is definitely worth $45 more. Click the link below for proof. http://www.anandtech.com/bench/Product/289?vs=202
1. I didn't catch that. I wouldn't use a "Blue" as a boot drive though. WD Blacks are okay if he has to have WD.
2. I noticed that you changed the PSU. You must've been writing your post while I was writing mine.
3. I've only built one rig with an MSI motherboard...P67A-C43 I believe. It was pretty straightforward, although it took a bit to find the manual fan control in the EFI. It's my dad's rig and it works great.