If the hard drive craps out or the data on the partition goes bad then you are hosed - at least for the short term. You can order restore CDs from Dell for about $30 USD just for this situation. Wasn't it really cheap of Dell not to just give you these CDs when you bought this PC ?
Replacement Restore/Installation/Recovery discs can be ordered from the PC manufacturer. You need to go to their web site (e.g., hp.com, dell.com) and navigate to Support, Customer Support or Technical Support. You need to find a link to a telephone number or an on-line "chat" session with a technical support representative. You may have to navigate thru many pages to find this information, but it will be there, somewhere.Before contacting the Support person have these things at your fingertips:
1) The model name, e.g., Presario, Pavillion, Satellite, etc. This is usually clearly printed or embossed on the case.
2) The model number, e.g., NX6325, D1600, etc. For desktops this will usually be on the front of the case. For laptops this is usually printed on the deck next to the keyboard.
3) The serial number. In the case of Dells this is called the Service Tag. This identifies the exact model, features and date of manufacture to the PC company so they know what PC they are dealing with. For desktops this will be on a sticker on the back of the case. For laptops this will be on a sticker on the bottom of the PC.
4) You may need the XP registration number, but probably not. For desktops this is often found on a sticker somewhere on the sides of the case in one corner or perhaps on the back of the case. For laptops the sticker would be on the bottom.
** Many PC manufacturers don't bother to post the XP registration number on the PC at all, so don't worry if you don't find it after looking thoroughly.
Replacement disc(s) typically run around $30 (USD). Shipping may be $5 extra. At any rate, $30 is a real bargain!
** Keep in mind that a Restore/Recovery will most likely wipe out all your added programs and any important files you have on the hard drive. If you want to back up your files you need to do this before restoration.