Looking for weightroom suggestions

so i am not a large guy (5’5, 140, 25 yrs old) and don’t intend on becoming one until genetics kick in in a couple years. i am wondering what you guys do in the weightroom. what i am looking for is a core set of exercises that work the essential muscles (1hr max). i am not looking to bulk up–i expect it a tad as a side effect of getting stronger, but i don’t really care about appearance. any suggestions–especially for the core area–are appreciated. as far what kind of shape i am in now, i just raced the muncie half last weekend in 4:43. if only i could swim!!! oh well, last year i did gulf coast in 6:10, so i’ll take the new PR. thanks in advance.

whiney