I have a triathlon in 6 days. Help me.

[TalkingDonkey]

Being the sucker I am for stupid athletic contests, I volunteered to represent my fraternity in the intramural triathlon this coming Sunday. It consists of a 1/2 mile swim, a 4 mile run, and a 16 mile bike ride. I consider myself to be in better shape than many people, I can run 2.5 miles in about 15 minutes and bike 9-10 in 20 minutes. However, a) these are the furthest distances I have ever gone and b) I have never swam for distance in my life.

Today I ran 2.5 miles and then biked 6, then followed it with some assorted ab exercises. Tomorrow I will go to the pool and swim - I know basic freestyle stroke technique but if any swimmers can give me pointers it would help a lot. I'll report back after my first swimming experience; I want to swim the full half mile. If I'm alive after that, I'll hit the streets and run.

Anyone who is experienced in events like this and especially training for them: how much better shape can I be in by the end of the week (I plan to make Friday my last training day) and what is the best way to get there? Also, I quit drinking and smoking til then...it's going to be a rough week.