Interfering with all computer data

I am interested in getting started in computer repair. I have seen many computer diagnostic boards that you plug into a PCI slot. They will tell you if the motherboard, power supply, memory, processor, etc. are dead or dying. Anyone have any experience with these? I DO NOT want diagnostic software, I want information about a diagnostic CARD. Are these worth the money? Do they work? Can someone recommend a decent one? Thanks for your help!

I have windows vista ultimate full version on my desktop pc and someone must have missplaced my installation disc and i need it to boot from if i need to repair or reinstall windows vista again! i am not going to pay for another new OS software in a store, all i need is a used disc or can i make a bootable copy off my OS?

My Windows Xp Disk Cleanup is Taking Hours! And I have still not reached the screen to direct it what to clean up. It's been scanning. Is There a Better Way to Clean up the HD? If software is an idea; I'm on a budget. Preferably I'm looking for good ad-free freeware or very inexpensive software.

Have you found Registry Cleaners to be safe, and are they effective in enhancing the performance of a computer? I ran a free scan from Regcure, and they supposedly found over 1,000 fixes. I’d like to speed up my computer, but am hesitant to use this, as I might delete something I shouldn’t. I guess my main question is whether they make a big difference to the computer, making the risk worth it. Thanks for any advice.