Best way to reinstall Mountain Lion on MBP?

Question

Hi.
My wife has had a MacBook Pro since 2009. Over the years it has become soooooo slow. She's got tons of stuff on it including old versions of software, and programs she never uses. Honestly, I think it's just bogged down from all her crap over the years. So here's the problem I'm having. I want to back it up and do a fresh install, but I don't want to use Time Macine because I'm afraid all of her old programs and bugs and such will just go right back on her computer. So the only thing I've come up with is clicking and dragging all of the folders onto an external drive and then back again. Is there a better way? A better program or process or tutorial? Any advice would be massively appreciated. THANK YOU!
Specs
Mac OS 10.8.4
2.53 GHz Intel Core i5
4 GB 1067 MHz DDR3
500GB HDD

Answer 1

If there is only one account, your Wife's, than you can just drag the "Macintosh HD" onto a large enough external hard drive. (***I would highly suggest you check to make sure the same amount of GB are on both drives after you have moved it all over to the external hard drive. You can do this by:
          Click on the Apple in the left top corner.
          Click about this Mac
          Click more info
          Click storage
hope this solution works!)
To reinstall Mountain Lion from scratch, follow these instructions below:
Choose Apple menu > Restart. Once your Mac restarts (and the gray screen appears), hold down the Command (⌘) and R keys.
If you’re not connected to the Internet, choose a network from the Wi-Fi menu (in the top-right corner of the screen).
Select Disk Utility, and then click Continue.
Select your startup disk from the list on the left, and then click the Erase tab.
From the Format pop-up menu, choose Mac OS Extended (Journaled), enter a name for your disk, and then click Erase.
After the disk is erased, choose Disk Utility > Quit Disk Utility.
Select Reinstall OS X, click Continue, and then follow the instructions.