The purpose of a non-compete clause is to prevent you from hijacking your employers clients or other actions that could damage your current employer when you leave. It is quite common in sales jobs or jobs where your primary responsibility is to develop relationships with clients. There are people who get jobs with companies for the sole purpose of moving their business to another company. I require them for some of my employees.

I might not be particularly big but I do shower regularly

Six months is trivial. It hinges on how similar is same. And then doing something about it means the legal cost of showing damages because they won't simply sue for arbitrary penalties without being harmed because the award can only be based upon the dollar value of the damages they can establish they suffered. Transferring trade secrets has no time limit so this is really little more than boiler plate.

                  Sorry Terelek but that is the way of the world.  All buisness decissions are made with the idea of makeing the owner(s) more money while  protecting their company secretes and protecting their markets. You can always refuse to sign the contract but you wont get the job.  

Agreed.

Every time I've heard of it going to court the judge threw it out as an unreasonable demand against someone whos learned skills that have earned them higher wages. The courts won't make you work at McDonalds when you could be at wall street or working for NASA.

I've broken many of them. I smirk every time I'm asked to sign one.

 A contract is simply a promise between two entities, you and whatever company- the promise can be whatever the two of you imagine. True, non compete clauses are rarely enforced unless direct financial harm is suffered by the company, this is simply because a company has no reason to spend money on lawyers, filing fees, etc.  unless the harm they received is significant enough to justify the expense. As a personal moral standpoint I think one ought to attempt to keep all promises they make.

You know the promise demanded before you make it, if you think it is too much you are free to refuse. Many legal promises that people make are promises I believe are foolish; for example, marriage is a foolish promise but people should be free to make it and the state ought to enforce whatever contract people make between themselves foolish or not. I think there are many situations in which a non compete clause is very logical simply to prevent assholes from screwing the company over. While I  probably would never sue anyone over one if I believed they did not intentionally screw me, it is important for me to know that if someone did intentionally screw me I have the option of seeking damages. 

well I needed this contract that's why I signed even if I don't agree with the clause. This contract is not negotiable. Actually it was this first contract that gave me enough experience to get this second one.

My other employer knows about this clause and wants me to wait six months before starting. But I still asked them like: "do I really need to wait that long?"

I don't see how would they know I'm going to work for the competition, unless someone tells them.

There is no way I can do much damage to my current employer. They know how each other works. And that's is not my goal (to screw my current employer). My goal is to get much better working conditions for myself.

It's still a dumb clause given the nature of my work and I believe it's only in place because of the huge wage difference between the 2 companies.

Another point to consider, would be the fact that the new employer would see you have a reputation for not honoring contracts.  As a new employer, I would be hard pressed to hire someone that I couldn't trust.