I just installed the game but I having issues in setting the controls right. When I first started out, every time I would hit the left button it would swing the car all the way to the left. I noticed when I set the saturation lower, It became easier to turn. Though every time I'm of the track, I will still spin out of control if I slightly tap let or right. Any suggested setting?

You really, really need some other form of controller for this game. I've got a 360 Controller for WIndows and that works well enough. Although it's all too obvious that a wheel is what you'd need for maximum performance.
Even if you bought a $10 controller you'd be better off than trying to play it with keys. But ideally you want something with analogue stick(s) for greater precision, like the 360 controller.

Well it is meant to be a simulation. Even if it's not exactly GTR2 when it comes to punishing realism, you've still got to have something more than keys. You can get away with keys to a degree on something like FlatOut but even then it's not ideal by a long shot. Racing games and keys just don't mix.
What's the problem with the Sidewinder? Is it a driver issue or will it just not work with the game? If the game doesn't recognise it you could try using Xpadder.

Maybe it's just me but I have done very well using keys with Flatout and project Torque and any game that has had vehicles in it. So I guess it varies between people. What I was trying to say is that by default, a PC game in general uses keyboard and mouse which the average customer will most likely expect even if it is a simulation. I believe it is an issue when a PC game relies primary on a device that the majority will not own by default. They probably will not know that they need a steering wheel or a controller which will mean they will think the controls are broken or unoptimized. If that is the case then the game box or description should state that ether a controller or a steering wheel is required. Also some people may not be able to afford another control device when they by this game so they will be left with an unplayable game.
We do need to post some keyboard setting to make it comfortable to those that only have a keyboard and mouse.

Well I played both Flatout 2 and Race Driver 2 with keys to moderate success. But this one is a bit more demanding as you've already realised. The problem with keys is their completely binary nature. They're either pressed or they're not. There is no pressure sensitivity that would help determine how hard you wish to turn, accelerate and brake. Games like this are only going to further exploit more advanced control methods. So you can only consider buying a controller an investment. As mentioned, the 360 controller is pretty good.

The out of control thing seems to only happen with the GT events while dune buggy like events always push left. I have been able to get better and control with some moderate success. The game pad I used didn't make a difference. By the way, have you experienced any issues with tweaking your vehicle in simulation mode? I can only exit but I can't keep my changes.