What you're asking for here is the kind of thing that administrators of Windows-based networks can do easily by using group policies. But I'm guessing that you're asking about a standalone installation, in which case there's no option to install Word (or, more generally, Office) for only one or some of the machine's users. Instead, the installation routine automatically makes Word (or Office) available to all users.
The best fix for this problem is to get another computer for the other users. The next best fix is to set up your computer as a dual-boot machine: one operating system with Office (or Word) for you, the other operating system without it.
If neither of these simple fixes appeals to you, follow this involved series of steps to approximate the effect you want. You'll need a copy of Tweak UI (
http://www.microsoft.com/windowsxp/downloads/powertoys/), as well as access to the other user accounts on your PC:
If you haven't already applied a password to your user account and made it private, do so. Choose Start » Run, type
control userpasswords, and press Enter to open the User Accounts window. Click your account, click Create a Password, type the password twice, and click the Create Password button. When Windows XP asks if you want to make your files and folders private, click the Yes, Make Private button.
Install Word (or Office) in a private folder within your user profile, rather than in the Program Files folder (the default and recommended location). That way, other users won't be able to access it directly through Windows Explorer. Even when you do this, however, the installation routine creates Start menu shortcuts and other associations that let the other users of your computer start the Office applications. You'll have to deal with these as well.
Still in your user account, open a Windows Explorer window to the Documents and Settings\All Users\Start Menu\Programs folderthe folder that contains items that appear on each user's Start menu. Choose Start » Run, type
%userprofile%\Start Menu\Programs, and press Enter to open another Windows Explorer window to your own Programs folder. Drag the Microsoft Office folder from the all-users' Programs folder to your Programs folder. Go up one level in each window to the Start Menu folder, and drag the New Office Document shortcut and the Open Office Document shortcut from the all-users' folder to your folder. This removes the Office-related items from the Start menu.
Log on to the first of the other user accounts and do the following:
Run Tweak UI and use the Templates feature (see Figure 1-3) to delete all the Office-related items from the New submenu on the context menu for a Windows Explorer window (or the Desktop).
Figure 1-3. Use Tweak UI to remove Office items from the New submenu of the Windows Explorer shortcut menu to prevent other users from running Word.
Choose Start » My Computer to open a Windows Explorer window; then choose Tools » Folder Options and click the File Types tab. Click the File Types column heading to sort the Registered File Types list alphabetically. Scroll down to the items starting with "Microsoft Office" (for Office 2003) or "Microsoft" (for Office XP or Office 2000). Delete all the Office-related items that you can dispense with, and change those you must keep so that they are associated with other applications. For example, you might associate the .doc extension with WordPad or another word processor. Scan down the list for Office icons in the Extensions columnfor example, "Outlook" items are listed separately, and the Rich Text Format file type is usually associated with Wordand delete or change them as necessary.
Repeat Step 4 for each of the other user accounts that you want to restrict.
If a user starts one of the Office applications, the Windows Installer installs that application and its helper applications in the Program Files folder and creates a Start menu item for that application if there isn't one already.