Junk hdd's that come in most big brand names typically go bad often (ESPECIALLY laptops). I have a Maxtor from 1998 that still spins up and runs fine. Not saying high end non-ssd's don't die, but they don't go bad nearly as often in my experience.
I work on PC's on the side every now and then, and I agree most of them are HDD-related issues. I'm a WD fan, myself. I have a 1TB RAID 1 w/WD "black" drives (7200rpm) and a 320GB RAID 0 WD "black" (7200rpm) drive and have not had any problems in over 4 years.
The application issue could be several things. A dual core and 2GB RAM is far from "up to par" for today's technology standards. I run a Linux webserver on a Celeron (single core) piece of crap Dell Dimension something with like 768MB/RAM and it runs like a dream. Then again, having no GUI helps. Boots up much faster than my 4+ year old i7, 12GB RAM desktop running Win8.
Take a backup of your computer, remove some bloat (msconfig to clean up startup apps and run ccleaner to clean up temp files/registry) and you may notice a difference in performance. Reinstalling Windows may help, too. Do some hard drive diagnostics to make sure the drive is okay.
