which one to choose

Hi 

I have been thinking to change to a macbook pro. I want a 13 inch and just to save some money I was thinking to go for a refurbished one. I was thinking that an older core2duo with dedicated graphics would be as gd as i7 or there is greater difference amongst them?
I have shortlisted these three notebooks and I need advise for which one to go for.

1) Refurbished MacBook Pro 2.66GHz Intel Core 2 Duo for $1161
Originally released April 2010
13.3-inch LED-backlit glossy widescreen display
4GB (2 x 2GB) of 1066MHz DDR3 SDRAM
320GB Serial ATA @ 5400 rpm
8x double-layer SuperDrive (DVD±R DL/DVD±RW/CD-RW)
NVIDIA GeForce 320M graphics processor with 256MB of DDR3 SDRAM shared with main memory

2) Refurbished MacBook Pro 2.3GHz dual-core Intel i5 for $1199
Originally released February 2011
13.3-inch (diagonal) LED-backlit glossy widescreen display, 1280-by-800 resolution
4GB (2 x 2GB) of 1333MHz DDR3 SDRAM
320GB Serial ATA @ 5400 rpm
8x double-layer SuperDrive (DVD±R DL/DVD±RW/CD-RW)
Intel HD Graphics 3000 with 384MB of DDR3 SDRAM

3) Refurbished MacBook Pro 2.7GHz dual-core Intel i7 for $1449
Originally released February 2011
13.3-inch (diagonal) LED-backlit glossy widescreen display, 1280-by-800 resolution
4GB (2 x 2GB) of 1333MHz DDR3 SDRAM
500GB Serial ATA @ 5400 rpm
8x double-layer SuperDrive (DVD±R DL/DVD±RW/CD-RW)
Intel HD Graphics 3000 with 384MB of DDR3 SDRAM


I am interested in the first one coz its cheap but i am not sure if it right value for money. the hard disk size is not an issue, I just want the machine to perform well for the few things i am going to on it, which consist of documents, some programming and thats about it. so please help me and let me know if i should take the cheapest one or i should go with some other option.