Here's whatsnew since 8.00:
GameEx 8.04
-Fixes MAME launch before command when in screensaver
-Fixes dialog text colour to be white instead of black in default (media centre) theme

GameEx 8.03
-Updated Media Center theme thanks to Alan (AKA Amos)
-Fixes importing MESS emulator configs
-Should fix hideos.exe not always showing
-Fixes window not returning to correct position after running a game

GameEx 8.01
-Supports MKV Videos (codecs required)
-Upgrading GameEx forces a re caching of graphics. Should fix a few issues
-Emulator groups now properly turn off any databases

Get it here:
http://tomspeirs.com/gameex/default.aspx

-Trebor