180 GB would be an extremely old HD ... If an SSD is not in the cards for budgetary reasons, I'd suggest an SSHD
If it is a 180 GB drive that means to everybody else who doesn't speak "marketing", it's a 167 GB drive. With the recommended 15% free you are down to 142 GB ... Windows folder is good for 50 GB, main user file 10GB .. with other odds and ends including uninstall and recovery files, after 6 months you are looking at 80GB ... leaving just 62 GB for programs and games ... GTAV is 95 GB
A newish performance 7200 rpm HD boots in 21.2 seconds
SSD boots in 15.6
SSHD boots in 16.5
For gaming SSHD is 50% faster than a performance oriented HD such as the WD Black
http://pcpartpicker.com/products/internal-hard-drive/#t=1&i=25&f=2&sort=a10