Will having two OS' mess up my computer?

[Guest]

So I am getting a new computer with a 1tb HDD and a 250gb SSD, and installing Windows 8.1 on the SSD. But I am also putting my old PCs hard drive, which has Windows 7,in the new PC. Will this screw it up, and if so what is the safest way to uninstall Windows 7 of the old hard drive?

 

[Someone Somewhere]

No. It's fine. Just make sure that the SSD is higher than the boot order of the HDD.

 

[Guest]

Thanks for the help!