How long have you had Windows installed on your PC, they tend to slow down over time, due to multiple things.
- Software being installed/uninstalled leaves traces that make your windows registry fat.
- Spyware, Virii clog things up
- Too many startup items at windows boot.
- conflicting or ghosted drivers
You basically need troubleshooting , and online that takes forever, if you can your best bet is to reformat, as stated above. If not, try a tutorial on MSConfig, you may simple need to eliminate extra overhead at boot
