Are people who ask this kind of stuff, making us spend a lot of time to read this kind of bullshit, naturally stupid and have nothing really useful to do with their free time?

Some of my recent customers' computers face this issue once in a while. It seems that people forget about hardware cleaning. Most of them think that just software maintenance is Ok. I've once found a high-speed computer performing tasks really slow. I just opened it and cleaned it up. The display card was trully dusty. After that, the computer went back to its usual performance.
Also, take a look at Event Viewer, seek for warnings and errors. That may give you more clues about what the problem can be if it keeps slow after cleanup.

I've learned some tips from a general security consultant while he was being interviewed on a TV show.

I don't remember all of it, but one of the tips I remember by heart is: Always insert the wrong password first. Then, you go back and put the correct one. If there is anything "listening" to your password, it will catch the wrong one. I don't know how effective this can be, but you know, any defense you can use is worth when it comes to your security.

You need to stop analyzing the box and reach out it's qualifying contents. Drive your questions towards that and you'll end up having non-discriminative questions with better information about the applicants. Look at each one as if they where exactly the same box and all you want is to know what's inside. That will keep you away from the law trouble and will make you a better interviewer. But, in the end, just like the candidates you intend to interview, it's not how old they are that will make them better employees, but how they deal with new experiences and what they keep from those experiences that will make them better. The same can be told about you. I assume that, if you came here to ask, you don't have the required experience to do it. So, why don't you ask someone with more experience (younger or older, doesn't really matter as long as he/she has proven experience) to guide you through this process? Just wanted to share one more thing. The way you made your question shows me that you have already made up your mind about hiring someone older and just came here for "endorsement methods" for you to present as criteria during the process of selecting an applicant. That seems true prejudice and, if that is correct, I think it's time for you to think over your concepts. The world has changed. Prove of that is that something never imagined for most people outside US happened, Obama will run the one of the most admired countries in the world. Nothing against McCain, but people here in Brazil were cheerful and joyful in the end of US elections. Think about it...