Well, fortunately I had a mother and father who were both greek and were encouraging me to rush since, oh about 5th grade lol... I was told about the high ideals of scholarship to the Greek Community, the involvement, etc... I was rushed by my own parents lol!!
But... I had an Aunt who was against me joining anything... she basicially said that greek organizations focus on drinking and partying... and that certainly isn't true... people, like my aunt, who aren't greek, will generalize and make assumptions...
I definitely encourage you to go through recruitment! It's a great way to meet people and a wonderful way to get involved on campus... if your parents are still adamant on you not joining a greek organization, check and see if there is a parent's guide to Greek Life in your Student Life office... I know at my school there are plenty! This helps parents get an insight to what Greek Life promotes and eases them a little bit...
I agree with Delta Beta Baby, don't be the girl who pledges and then has to drop because she didn't tell her parents... that only makes things worse for the sorority and you

I'm sure you won't, but it's better to tell them upfront than to lie to them... it happened to a girl in my pledge class when I pledged in Fall 2005... not pretty...
Best of Luck to you!
-Kalyn