PC Running Slow and Crashing

My PC keeps freezing and laging, its really slow and takes longer to boot. It does that in the middle of my game and i have to restart it. 

I am pretty sure its the HDD but i just got it a few months ago.

Just want to know could it be something else before i try to reinstall my  OS on another hard drive. 

need more info...  all system specs, what OS, how old, what game...


hard disk: western digital blue 
specs: 4gb corsair ram ddr2, intel core 2 duo @3ghz, amd radeon hd 6570 (potato)
OS: windows 8.1 enterpriese
Game: every game but i only played WOT this week because nothing else wont even start