AnthoRasher :
Is it possible to just use the old HDD in a new PC so I wont have to purchase windows again?
2 considerations - Operation and Licensing
1. Operation. It will almost certainly not boot from that laptop drive. Requiring a full reinstall.
2. Licensing. That OS is almost certainly a preinstalled OEM OS, which is licensed to that original laptop motherboard.
So it won't work.
3. Even if 1 & 2 were not considerations....now you have a laptop with no drive or OS.
Solution? Sell the laptop. Buy an OS with the proceeds, and go out to dinner on the remainder.