No matter what way you choose I think it is important you have your Windows 7 license key from the existing install. Check to see if it is written on the computer (somtimes a sticker on the top, back, or bottom (if a laptop). Or if you can still boot this hard drive then you can get the key using freeware like
SIW; install and run SIW and go to Software ... Licenses, copy down the Windows Product Key carefully and store it in a safe place (never share it or list it online). If you end up cloning then it should just copy over but in case anything should go wrong you really should have this stored away.
I also highly recommend that you burn an actual copy of W7 to a DVD; you will need a DVDRom drive and a blank DVD (or if you have an empty 4GB flash drive you can choose to create a bootable flash drive). Download W7 SP1 and burn it to DVD. You didn't say if you have Home Premium, Professional, or Ultimate but get the correct W7 64-bit (x64) to match the version you currently have installed from the links
>>HERE<<. Use
IMGBurn (or other burning software that knows how to expand image files) to burn it to DVD; best to burn at 3X with verify enabled. The reason I recommend you have a W7 DVD (or W& flash drive) is because even when I clone a hard drive I always end up needing the DVD to fix the boot sector or if you do a full install then of course you need it for that.
Now, the fact is that cloning is definitely the easiest. Most new hard drives actually come with the cloning software, then you simply hook up both hard drives to your computer and tell the software to clone the old hard drive to the new one. then you remove the old hard drive and attempt to boot to the new one (as I said above, I almost always must put in the W7 DVD to fix the boot sector once before this works).
BUT if you prefer to do a fresh install rather than cloning then you will need to back up all your data and settings (normally to an external hard drive). I recommend Windows Easy Transfer to do this (it is built-in to W7). After you have all your data backed up you replace the old hard drive with the new hard drive and run the W7 installation DVD (or flash drive). Then you restore the Windows Easy Transfer back-up. And then you must reinstall all your programs and games such as Microsoft office, IMGBurn, Minecraft, etc. As you can see this is a whole lot more work than just cloning the old hard drive to the new one.
