not sure which upgrade to go with for my computer.

[breadisfunny]

i can only choose one so i would like to know which is a better performance/budget wise.
1. replace my old sandy bridge dual core 3.4 ghz i-3 2120 (non overclock) with a intel core i-5 3570 ivy bridge quad core 3.4ghz (non overclocked) for 210$+tax+shipping) (i have the updates to support the new cpu.)
2. replace my old dell st 2010 21" monitor with a new 21" monitor. (90$ for refurbished or 110$ for new) current monitor will randomly go to sleep and not wake up for no reason.
3. replace my old nvidia gt 560 with a 1gb gddr5 memory with a nvidia 660 (180$ with rebates)

also is buying refurbished a bad idea with monitors?
not really looking to buy top end components just ones that a decent upgrade form what i have yet within my budget.

[Toffie]

I would go for a 660 which likely will resolve your monitor issues, it's most likely a driver issue depending on the driver you're using.

[chazus]

Going from the 560 to 660 isn't a huge jump. Personally, I'd go with something like this, and then get a used monitor or something for $50 or ask for a gift from family.

PCPartPicker part list
CPU: Intel Core i3-4130 3.4GHz Dual-Core Processor ($119.99 @ Newegg)
Motherboard: Asus H81M-K Micro ATX LGA1150 Motherboard ($42.99 @ Newegg)
Total: $147.98

[breadisfunny]

about the cpu...i really want to upgrade to a quad core since games are starting to utilize all four cores now.

[chazus]

about the cpu...i really want to upgrade to a quad core since games are starting to utilize all four cores now.

They really aren't. There's like... one game. And the i3 has hyperthreading. Any performance gain is not worth the extra $100.