How to change file associations in XP
If a new program changes a file association such as if you install a graphics program like PhotoShop, you might find that it is now the default program to open picture files like .jpg and .gif, even though you prefer to have them opened by the Windows Picture and Fax Viewer. Luckily, it's easy to change the file associations so that files with the selected extension will open with the program of your choice.
Right click the Start menu and select Explore.
In Windows Explorer, click the Tools menu, then click Folder Options.
Click the File Types tab.
In the list of registered file types, scroll down to the file extension whose association you want to change and highlight it.
Click the Change button.
Scroll through the list of programs that can open the file type and select the one you want to use as the default. Be sure the box labeled "Always use the selected program to open this kind of file" is checked.
Click OK.
You can click the Browse button to look for the program if it doesn't appear in the list.