Here's whatsnew since 7.50:

4th February, 2007 - GameEx 7.55
Fixes catver.ini
Fixes multiple MAME rom paths
There is also an offline install for the game manual viewer on the download page


3rd February, 2007 - GameEx 7.53
Fixes and compatibility updates for Windows Vista and 64 bit versions of Windows
Should now run out the box on Vista
The Setup and applications have been digitally signed.
Ben Baker's Setup Wizard 1.74
Fixes picture and slideshow transitions with latest ATI video drivers and on Vista.
Asta La Vista.


1st February, 2007 - GameEx 7.52
LCD/LED Plugin 1.5 Beta
Ability to have custom MAME lists in MAME32 ini format
Ability to import MAME32 Favorites.ini
Fixes .net framework error at startup
Should fix install exception if your GameEx install is old
Updated MAME support files
Fixes issues when using latest versions of catver.ini

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

-Trebor