Im making a new PC build and I wanted to know if I could possibly use my current laptops HHD for my main hard drive. Is it possible?
Assuming it is a sata drive, yes, no problem.
I used one in a small form factor build.
If your case does not have a 2.5" hard drive mount, you may need a $5 adapter to fit a 3 1/2" hard drive mount in the case.
As a main OS drive, it will not be so good. Laptop drives are slower to conserve battery power.
If you used a small SSD for the os, a laptop drive would be ok as a storage device.