I think the requirement of the OP is Office work which he has explicitly mentioned , not to run games or highly multi-threaded applications. And for this kinda work a bigger display is suggested. And for that kind of requirement, between a Athlon II X3/X4 and an Sandybridge 2100 processor, there is hardly any real world notifiable difference. And AMD 4250 onboard graphics is better than the Sandybridge 2100's onboard graphics.
Here is my suggestion:-
Athlon II X4 635 @ 4K
Gigabyte GA-880GA-UD3H @ 5.45K (with SATA 3, USB 3.0 and 2 PCI Express X16 @ X16-X4 mode and upcoming AM3+ Bulldozer CPU support)
Corsair 1333 MHz 4 GB DDR3 @ 2K
Seagate 500 GB SATA @ 1.7K
Dell ST2220M Full HD LED Display @ 8.1K
Cooler Master Elite 310 @ 1.5k
FSP SAGA II 500W @ 2.3K
Logitech Mouse/Keyboard combo @ 0.8K
LG 22X SATA DVD R/W @ 0.9K
Total: 26.75K.
Now if you want, go for a 23"/24" display. There are Samsung models available @ less than 10K.