Sometimes the staff at a vendor do not have the real knowledge of the hardware, and the printed spec shows too little. Most of the time, I always bring CPU-Z, Furmark, etc. with me in a USB. For Linux side, I got Hardinfo.
However, there are some cases that the vendors do not install any OS in the laptops. (or sometimes, they just install FreeDOS) In this case, if I want to know the real hardware inside these laptops, what are my choices?
I can think of using Ubuntu LiveCD, and download Hardinfo from there, that is if the vendor allows me to access their WiFi and run from LiveCD.
Linux live CD should do it, you may want to make a USB drive if there is no CD/DVD player or if it's broken. I don't know if boot disks like Ultimate Boot CD have hardware info utilities, but they may.