Hmm, the eternal question, ssd vs processer. Personally, I woul go with the higher CPU. You may suffer slightly slower loading times, but when gaming you will get better performence due to higher cpu. Nothing is more annoying than having an underpowered CPU. Also, with 128gb ssd, it will run OS fine, but not enough space for many games, so they will have to be on the hard disk anyway.
As far as I know you can upgrade and put one in later if you wish. This may void warrenty (you will have to check) but it is far easier to swap in a ssd than change a processor (and a lot cheaper, you are not getting rid of anything)
Go with the HDD
Tom