this is the wrong place to post, there is a Suffplug-NG thread.
as for your problem which dll did u extract to the system folder ? the one in the stuffplug-Ng rar or the cximage.rar file ?
well firstly u need to extract the
cximage.rar in the system 32 folder and rename it to cximagecrt.dll and then install
StuffPlug-NG.rar into the plug in folder (normally c:\program files\messenger plus! 3\plug-ins).