System Build Advice

All added up it comes to $558 so that leaves him $140 to spend.

There's 2 ways to go, he could get an i5-2400 for true quad core and have a longer CPU life(effective) or he could get a better PSU/Case.

The benefit for spending extra on PSU/Case(especially case) is it can carry over into new builds.

So I'd talk to your friend, and weigh what he thinks about the CPU or the PSU/Case. Educate him on Efficiency, Airflow etc. Then show him the i3-2100 in gaming benchmarks vs an i5.

But either way it may not be worth the extra money in his opinion.