Xrayracer,
Dennis hit it right on the number! Good suggestions. I would also go out to IMI on a nice weekend and talk to the drivers. You will be surprised at all the advise you will get. Everybody and I mean everybody is a supporter of kart racing-just a great bunch of guys.
Get your check book ready to get into tag the first year from scratch, you will spend ~$5-10,000.
Want to see you out there with us Tags. If you are real energetic-buy a Rotax and you can run:
Tag and Rotax Max Challenge races on the same race days on some tracks.
Good luck