i've done one like this too, and believe me mine was compacter (size, no compression) and offered more possibilities (like installing of multiple plugins) but had some security limitations that yours hasn't... i don't know if yours does, but in mine the plugin list was instantly refreshed and the directories were gotten from the registry. uninstaller was included and a log file next to it. entry in add/remove programs was there too.
hey, I've found a link!
http://www.nsrtech.net/~millenium/mppsgen.exe
problem is and will stay it's in VB, that's why TB's one in the plugin section is the most recommended one.