I have a cartoni beta tripod with cartoni legs. The problem is that the legs are very shaky. Any suggestions on how to stabilize the legs and make them more sturdy/solid.

change the tripod. there is no reason to have problem with a tripod used in normal conditions. Either there is a problem, or you are using wrongly (too heavy cam ?).
you can find nice tripod for $150. or legs only for less than $100
trying to fix this one could cost easily half this price (purchasing a spreader ?).
and you would end up with half good result.

Corey,
What condition are the legs in? New? Been through combat?
Make sure the locks and pivot points are good and tight, with minimal side-to-side play.
I haven't worked with Cartoni's legs (don't know how naturally prone to wind-up they are), but I've found their smaller heads to be a bit squirrely. If you have access to a different tripod/head kit of the same bowl size, you could trade the heads and see if there is any change with the different combination, then trade/upgrade to taste.

To help stability, you can anchor the top/center of the tripod to a sandbag with a ratchet strap. Or bag each leg. Or get your hands on a 100mm Ronford tripod....

The head works fine. Just serviced it. The legs have been through combat and anything else you can think of. I was thinking my camera may be to heavy, but the legs were used with studio camera's with the large viewfinders with no problems. Everything seems tight except for the spreader in the middle of the legs. i'm sure the fact that it sat in the floodwaters of hurricane katrina doesn't help the situation either. Can anything be done about the spreader.

I guess you could try to tighten the mid-level spreader as much as possible... it could also be the attachment points that are the weak link. If the legs were submerged in water (esp. with any salt content) for an extended period of time, there could be some internal corrosion/rust that may not be visible from the outside. Could try checking any bolts, nuts, washers, or pins on the legs and spreaders and replace as needed.