this is a full-featured, freeware software. You can add lots of freeware 'plug-ins' to it, to get a professional shopping cart.
Therein lies the danger. Some of these plug-ins require altering or overwriting the default cart files. When you try to upgrade the cart version later, you may 'break' it, by overwriting a plug-in, thus creating errors.
The trick here is to only install plug-ins that add files (rather than overwrite them) or that require minor alterations to existing files.
What I do is download all the versions of the plug-in type I need e.g. a WYSIWYG editor. I then choose the one which has the least files, or which creates a new directory for its files. If it requires that important files be overwritten, or is complex, I chuck it.
Mambo and Oscommerce. Don't try to integrate them! Hyperlink from one to the other. I've tried integrations of other softwares, like PhpBB and PhpNuke. Fine, when it works, but when you upgrade one or the other, arrgh!
*Keep databases separate*. If one goes skew-whiff, then at least the other will still work. Same goes for adding chat rooms and the like. If they're all running off the one database, and that database becomes corrupted ...
