Links Dialog

You can insert links to objects from any program that supports the OLE (Object Linking and Embedding) technology
In this case the document only stores the location of the file
Links are automatically updated by default (Tools > Options)(General tab) in 2003
2007 - Office > Options > Advanced - scroll down to General

The order of the links in this dialog box is not the order of the links in the document.

Office > Prepare > Edit Links to Files
SS

Alt + K + E
SS

Update Now - Only available if the link is not locked
Open Source -
Change Source -
Break Link - changes the object from being linked to being embedded.
Automatic update -
Manual update -
Locked - prevents the link from being updated
Preserve formatting after update -
Save picture in document -

To break a link that is being used in a document select (Edit > Links) (Break Link). The object will remain in your document although it will no longer be linked.
I would not advice linking either Excel charts or tables as this will increase the chance of Word crashing
You can prevent your links updating automatically when you open a document by changing your (Tools > Options)(General tab, "Update automatic links at open")

Shortcut Menu

When "an automatic" linked object is selected extra items are added to the shortcut menu
SS
Update Link -
Linked Worksheet Object - Edit Link
Linked Worksheet Object - Open Link
Linked Worksheet Object - Convert
Linked Worksheet Object - Links

When "manual" linked object is selected extra items are added to the shortcut menu
SS
Update Link -
Object - Convert
Object - Links

If you change an automatic link to a manual link this shortcut menu will only be changed when you close and reopen the document

In Word 2003 these options were also added to the bottom of the Edit drop-down menu

Important

If you insert large linked object or embedded object it may get cropped.
Word displays linked or embedded objects using EMF (extended metafile)