What's your budget?
If I were looking for a budget system for basic use I'd probably get an i3 or Haswell Pentium/z97 or H97/8GB ddr3.
So something like:
Intel Pentium G3450 $90
MSI H97 PC Mate Desktop Motherboard - Intel H97 $90
G.SKILL Ares Series 8GB (2 x 4GB) 240-Pin DDR3 $30
Add an SSD and it would be quite speedy.
You could certainly go cheaper, it's possible to spend less. The SSD would really have the most impact.