creating .msi files

I would like to know the name of a tool to repackage patch files downloaded from microsoft to .msi files. I do not whant to go down the .zap file route but i do whant to deploy the patches through group policy to my endusers computers. I am aware ofmicrosoft SMS server but Bill Gates has had enough of my IT budget for one year, Any ideas would be most appreciated
RGDS
PCStechnical