You will adapt in no time at all to a bigger screen, trust me. A screen that is too big of course is no good either if you don't have the space to back off a little bit, but going form a 19 inch to 24 inch or so is very pleasant.
Also, if you only use the PC for gaming I wouldn't recommend an i7, since it costs a lot more than an i5, but does not make much if any difference in gaming. I would save some cash and get an i5.