What processor should i build around

Core i5 lga 1156. Or you could go with an AMD system, but I haven't used one since socket 939 so don't take it from me .

Why the 620 over a 545? Either would work, but it doesn't seem like the OP is going to do much heavy multitasking, so wouldn't a faster dual core serve his needs better?

Here is a comparison of the 620 vs 550 BE (Doesn't have 545)... http://anandtech.com/bench/default [...] =106&p2=97

In most office related task, the slower 620 is better since they can utilize all four cores, which make it faster than a dual core. You have to remember in most "non-gaming" activities, a PC will be faster with a slightly slower quad versus a faster dual.

As you stated, the OP will be fine with either CPU. The OP would be fine even with the X2 250 or even a E5300. I just feel for under $100, the 620 is the better option.

Thanks for all the input. I am actually building a new pc for a friend. So let me give him this info, and see what he thinks. I might be back with more questions. In the mean time, if you have any other thoughts, I would very much appreciate those also.