Triathlon - Devising a training plan for a triathalon in May?

I am not a triathalete, but my college has a yearly triathalon that I feel like if I started working on I could do well at. I am very in shape from cycling, I do about 200 miles a week if I have the time. Swimming I don't do a whole lot of right now, but I am able to do 20-25 laps without a problem. Running is the issue. I used to run cross country in high school, but pretty much blew out my knee, and I haven't run 6 miles in 2 or so years. I am worried about being able to get back into that kind of shape by May, and not hurting myself again. If I start now I could probably build my way back up, but I was curious about your guys experience.
The distances are approximately 19.1 miles for the cycling portion (I think) 6.3 miles for the running, and 1 mile on the swimming.
Thanks!

There are schedules you can follow. Look at trifuel.com. Or if you want to throw down a little coin, you can go with an online coach, like Carmichael Training Systems (Trainright.com).
Sounds like you already have a good cycling base. This time of year you should work on getting a running base. Start with short slow runs, even mixing in walking, and gradually work up the miles.
The biggest challenge is likely to be the swim. One mile in open water, with a pack is a much different animal than 20 laps in the pool. If you're not already a gifted swimmer, check out the Total Immersion book, joining a Masters Swim team, and or lessons.

I recommend buying a book about Tri training. I have several, my favourite being The Triathletes Training Bible by Joe Friel.

In this thread I also linked some of my favourite threads on training, nutrition and setting up a schedule:

http://www.bikeforums.net/showthread.php?t=148335

For the run, you may want to consider something like the programs at www.posetech.com

They focus on proper running technique to avoid injuries. I am just starting it and I have a few friends who have had a lot of success with it (including a guy who just started running this year and turned in a sub-4 hour run leg at IM Florida).

Good luck!

Take it really slow if you have had knee problems with running. You have 6 months until the race, lots of time.

Go see a doctor in sports medicine. Perhaps stop by a local running shop and get a reccomendation for a doctor. A good sports-med doc will evaluate your stride and make reccomendations for running. Once you see a good sports-med doc, go out to a local running shop and get a good pair of running shoes. Don't go to a national chain! See the local guys, they will evaluate your feet and stride to find the right pair of shoes for your body.

Good luck and have fun!