i5 vs i7 confusion

[HimanshuUT]

Help me select one of these three laptops. Confused like hell between i5 with 1GB Graphics and i7 with 512MB Graphics.

HP Probook 4431S (2nd Gen i5/ 4GB/ 500GB/ 1GB) With 1 Year Onsite Warranty | eBay

Lenovo Essential G580 (59-348965) WITH BAG | eBay

HP Intel Core i7-640M Processor/4 GB/640 GB/14"/2Mega Pixel Web/512MB ATI Graph | eBay

Also suggest other laptops with similar or better config if available for less.
P.S.: Please suggest only HP, Lenovo or Sony as I don't think others have good built quality and/or after sales services.

 

[nandu26]

I think if you are not a gamer then corei5 is sufficient. I heard that corei7 generates heat but it will be faster than i5.

 

[aroraanant]

Please mention your requirements.