Three years ago, I bought a cheap Compaq tower, can't reemmber which model now. It came with Vista Home Premium. Which wasn't actually that bad of an OS. However, it was absolutely filled with HP/Compaq.... I want to use a C word, but I will just say "tripe" instead.
It even had an EULA from Compaq that I had to agree to before it'd let me use the hardware. I spent 3hrs trying to uninstall all that tripe. Eventually, I gave up, and went out and bought a retail copy of Vista Home Premium.
I could have downloaded a slipstreamed ISO like my friends suggested, but, yeah, I agree with Kymmy. Even the ISO is intellectual property. Even if you own a valid licence, it does not authorize you to download a copy. The licence only applies to the copy that came with the PC.
Turns out I wasted my money, as my best friend bought me a custom built Alienware desktop for my birthday a year later. With Windows 7.