The layout.ini file can also be deleted without a problem. *.ini files are ‘information
files’ that are used by Windows to make configurations. Layout.ini contains prefetch
information for XP's disk defragmentation system (defrag). Information in this file
is used by the defragmenter to move programs and files on your workstation's hard
drive to a more favorable location, speeding up direct read times.
http://www.windowsnetworking.com/pages/article_p.asp?id=394