A. Reformatting is the process by which you completely erase all data from your hard drive, eliminating your operating system, data files (word documents, excel spreadsheets, mp3's etc) and any and all software. It is an irreversible process. Once started, there is no turning back. Make sure you absolutely need to reformat before you dive right on in.
A. Sometimes as a user there are instances when cleaning the entire system will purge any defects of software conflicts. Sometimes there are programs that interfere with other programs in such a way that they render your system completely useless. Another reason would be contracting a virus. In order to completely insure the removal of a virus reformatting your hard drive may be necessary. When your computer seems sluggish and you haven't reformatted in a long time you might find a reformat will breathe new life into your machine. This is due to a large, cluttered registry and software applications eating away at all your resources.
Now that the formalities are out of the way here's a few tips to ensure a smooth format. These instructions are for Windows based computers so many instructions will be radically different for Mac/Linux users.
Follow the instructions to reinstall Windows. Once Windows finally finishes installing (usually 20 - 30 minutes) get your modem/network card drivers back on. After that, go download (unless you saved the drivers on cd) all the drivers for your peripherals.
Now that all your hardware works again, all you need to do is reinstall all your software programs (Office, Photoshop, etc) and put your data files you saved in step 2 back on the hard drive. NO : If you burned you data to a cd and are unable to edit/modify your documents, it is because when you record onto a cd you change a file's attributes to read only. In order to edit your document, you will need to find it in Windows Explorer and Right Click and view properties then UNCHECK the read only box.
Having two hard drives is ideal for frequent formats. Save all your data on the second hard drive and install all your programs on your first hard drive. When you need to reformat there is no need to do step 2 at all if you have all the drivers/software preloaded in a backup drive.
For the budget-minded, a recordable CD-ROM drive will help back up important static data (data that never changes like programs you use such as WinZip, mp3 software, or device drivers) such that you can have the Windows cd in one drive when you reinstall and your utility cd in the recordable CD-ROM.
Additionally, programs like Drive Image will create an exact replica of your hard drive. You can use this to save your computer state right after you reformat and install all your drivers/software so that whenever you need to do a reformat, you can simply restore your hard drive from the state your machine was in after a reformat. You can save this on your other hard drive to make reformats a one step process.