For web browsing and such, you do not need a discrete graphics card like a 7750; that id for gamers(you perhaps?)
You will also need to budget for an os which you did not include.
You also do not need a quad core cpu.
The Intel G530 would be fine. $50
Any socket 1155 motherboard will do. $50
Newegg has a corsair CX430 on sale for $17!! Good psu too.
A cheap case is OK $25
I don't think I would buy a refurb hitachi drive. Their reliability is not the best: http://www.behardware.com/articles/862-6/components-ret...