As stated, only difference is 2 cores/4threads vs 4 cores/eight threads. This only will effect some software. For 12 quid the i7 would be the better buy.
I have the Samsung RF711-SO1 (17 in, I5-2410m, 540m GPU, and Blu-ray/DVD-rw)
Was lucky found on sale for $750 USD (Don't you just love VAT).
My only complaint is (A) Moved the delete key - could get use to if I did not alternatly use other computers. (B) puting a USB Thumdrive (USB3) into either of the 2 USB3 ports kills the Wi-fi connection, posibly a setup proplem.