Hiya Martin,
The location of the WinFileCache in XP for CS4 is at:
C:\Documents and Settings\User\Application Data\Adobe\Dreamweaver CS4\en_US\Configuration\WinFileCache-3012BA81.dat
The User bit of the path will be your logged in ID.
The alpha-numeric characters between 'WinFileCache-' and '.dat' in the file name will be different every time.