Pretty hard for me...
You should also get a decent video card to play it at a good speed.
I didn't like the graphics and specially the speed. Everithing was set in low graphics, but it was pretty slow. (my card: FX5200)
The most disappointimg for me is that you can't tune your car. You can't do anything on it, except to chose some colours of the teams.
One of the best things in the game is the tutorial. It really helps a lot to learn to play. You can unlock tournaments when you win some tests.
It really cost a lot to learn to play ok. A simple error (like braking at the same time you're steering) makes you go to sand.
Don't forget, this game is a sim. If you tought it might be similar to nfs OR Gran turismo, you were WRONG. You'll be disapponted.