Do you mean to say that the option "Preview" is missing from the right-click menu and that you are unable to view the picture?
Could you also please tell us what is the image format like jpg, gif, png, tiff, etc....
Here are the steps to fix that.
Open up any folder and go to the Tools menu and select "Folder Options"
Search through the list of extensions and find the image format that you are unable to view.
[Windows XP supports the above mentioned formats as far as I know. Hope yours is one of them]
Here I've selected "GIF" and then click "Advanced"
Select "New" from the right hand side menu.
Type the following as shown.
Application used to perform action: "rundll32.exe C:\WINDOWS\system32\shimgvw.dll,ImageView_Fullscreen %1"
Click OK to save the settings
If you want "preview" to be your default command, select "Set Default" on the right.
[This makes preview the default command so that if you double click on the picture it loads the preview.]
Click "OK" and then "Close".
Here's a picture of the menu item "preview" that we just created.