Replace/Add the following files for the version you are updating to:
(If you dont have one of the versions between the one you have to
the one you are updating to then replace all the files from all the
versions in between plus the one you are updating to.)

 == ALWAYS REPLACE ==
globals.php

 == 5.1 from 5 ==
functions.php
load.php
modules/calendar/	(Check CHMOD Needed)
modules/en_board/mod.php
modules/en_board/admin.php
modules/en_board/messages.php
modules/en_board/display_forum.php
modules/messages/mod.php

 == 5 from 4.99 ==
modules/banners/mod.php
modules/banners/admin.php
modules/en_board/messages.php
modules/news/mod.php
modules/news/admin.php
modules/documents/mod.php
modules/documents/admin.php
modules/downloads/mod.php
modules/downloads/admin.php
modules/gallery/mod.php
modules/gallery/admin.php
modules/links/mod.php
modules/links/admin.php
load.php
modules/messages/mod.php
modules/gallery/mod.php
globals.php
rank_required.php
modules/pages/admin.php
top.php
functions.php
load.php
modules/ipbans/admin.php
modules/en_board/open_subsection_bt.php
modules/en_board/open_subsection_sf.php
modules/en_board/close_subsection.php
modules/banners/mod.php
modules/gallery/chmod.php
modules/shout_box/mod.php
modules/ipbans/mod.php
modules/pages/mod.php
modules/shout_box/include.php
modules/en_board/display_message.php
modules/en_board/rank_required.php
admin.php
modules/gallery/
modules/banners/admin.php
templates/blue_metallic/
templates/dark/
user_info.php
modules/en_board/rank_required.php
custom_user_info.php
user_info.php
bottom.php
modules/messages/
modules/ipbans/admin.php
top.php
install.php
include/styles.php	(CHMOD TO 0666)

 == 4.99 from 4.98 ==
top.php
users_recall.php

 == 4.98 from 4.97 ==
modules/en_board/mod.php
modules/en_board/admin.php
modules/en_board/open_subsection_bt.php
modules/en_board/close_subsection_bt.php

 == 4.97 from 4.96 ==
functions.php
modules/en_board/mod.php
modules/en_board/display_message.php

 == 4.96 from 4.95 ==
modules/en_board/mod.php
modules/en_board/display_message.php

 == 4.95 from 4.94 ==
admin.php
load.php
functions.php
modules/en_board/mod.php
modules/en_board/admin.php
modules/en_board/messages.php
modules/en_board/forums.php
modules/news/admin.php
modules/news/include.php
modules/documents/mod.php
modules/documents/admin.php
modules/downloads/admin.php
modules/links/admin.php

 == 4.94 from 4.93 ==
top.php
load.php
control.php
custom_variables.php
modules/en_board/display_message.php

 == 4.93 from 4.91 ==
top.php
load.php
control.php
modules/links/mod.php
modules/news/include.php
(You will need to delete all the users since there is a new
encoding system, if you dont want to do this then donnot upload
top.php, load.php, control.php)

 == 4.91 from 4.9 ==
modules/ipbans/

 == 4.9 from 4.86 ==
admin.php
modules/news/icon.gif
modules/pages/icon.gif
modules/en_board/icon.gif
modules/downloads/icon.gif
modules/documents/icon.gif
modules/links/icon.gif

 == 4.86 from 4.85 ==
modules/en_board/display_forum.php
modules/en_board/messages.php
modules/en_board/images/

 == 4.85 from 4.84 ==
(There are no actual updates on this version exept it comes with different templates
than the previous one and comes with different content in header.php and footer.php)
header.php
footer.php
templates/blue_metallic/

 == 4.84 from 4.83 ==
functions.php

 == 4.83 from 4.81 ==
functions.php
modules/shout_box/include.php

 == 4.81 from 4.8 ==
modules/en_board/messages.php

 == 4.8 from 4.6 or 4.7 ==
functions.php
modules/en_board/admin.php
modules/en_board/display_forum.php
modules/en_board/messages.php
modules/en_board/images/
modules/en_board/styles.php	(optional)

 == 4.6 from 4.4 ==
load.php
functions.php
control.php
users_recall.php
modules/links/		(new module)
modules/en_board/display_message.php

 == 4.4 from 4.3 ==
modules/en_board/admin.php
modules/en_board/mod.php
modules/en_board/forums.php
modules/en_board/display_forum.php
modules/en_board/open_supsection_bt.php
modules/en_board/open_subsection_sf.php
modules/en_board/close_susection.php

 == 4.3 from 4.2 ==
admin.php
load.php
index.php (optional)
includes/set_vars.php
modules/en_board/mod.php
modules/en_board/include.php
modules/en_board/variables.php
modules/en_board/messages.php
 ::New Variables::
<#en_board_lpf#>

 == 4.2 from 4.1 ==
modules/en_board/mod.php
modules/en_board/messages.php
modules/en_board/display_message.php
modules/downloads/admin.php

 == 4.1 from 3.8 ==
load.php
user_info.php
modules/en_board/mod.php
modules/en_board/messages.php

 == 3.9 from 3.8 ==
(skipped to 4.1)

 == 3.8 from 3.7 ==
modules/news/rss.php

 == 3.7 from 3.6 ==
functions.php
modules/news/admin.php
modules/documents/
(Dont forget to CHMOD.)
(Use "CHMOD Needed" on admin modules.)

 == 3.6 from 3.5 ==
control.php
load.php
header.php (optional)
footer.php (optional)
control_content.php (optional)

 == 3.5 from 3.4 ==
functions.php

 == 3.4 from 3.3 ==
globals.php

 == 3.3 from 3.2 ==
functions.php

 == 3.2 from 3.1 ==
 - Bugs Fixed!
functions.php
admin.php
install.php

 == 3.1 from 2.9 ==
functions.php
admin.php
install.php
header.php
footer.php

 == 2.9 from 2.8 ==
functions.php
admin.php
header.php
footer.php

 == 2.8 from 2.7 ==
modules/downloads/mod.php
modules/downloads/admin.php

 == 2.7 from 2.6 ==
functions.php
admin.php
install.php

 == 2.6 from 2.5 ==
modules/banners/
modules/en_board/admin.php

 == 2.5 from 2.4 ==
load.php
top.php
functions.php
modules/downloads/rank_required.php

 == 2.4 from 2.3 ==
load.php
modules/downloads/mod.php

 == 2.3 from 2.2 ==
load.php
modules/news/include.php
modules/board/messages.php

 == 2.2 from 2.1 ==
modules/news/include.php
modules/board/messages.php
modules/board/mod.php