Foundation was a great idea. It used to be 500 usd, i remember well because i purchased one.
It included a ton of stuff and was a fully functional version of xsi that had modeling, texturing, rigging and rendering, unlike the other similar alternative on the market back then, which was G-Max, if anyone remembers that, which was a good initiative, but well, it was a stripped down version of max that did only modeling and texturing (yes i know it was free).
Foundation was missing stuff that was included in essentials for 2k, and advanced for 7k, things like hair, syflex, rbds, cdh, satellite and standalone mray etc.
A great deal imho, and one that should have similar counterparts in all the packages (like the 99 bucks apprentice houdini license).
Now i'll add my side of the rant. You have been warned
Been using xsi since 1.0 in 2000. I'll never forget the day i got those 2 cd's in the mailbox, with the red velvet logo on them. I stopped using max the day i received that package, and i never looked back. Been keeping my eye on it ever since jurassic park hit the screens, but never had access to it, until they sent those 2 demo cd's. What a day that was.
It's actually hard for people to understand how emotional someone can get about a package, but i think most xsi users are like this. We've all felt like underdogs through the years, and i think that helped the small community bond even more. I don't think i've met a nicer and more open bunch than the xsi folks. So when autodesk puts their hands on a piece of your life, and starts ripping it apart, it's only natural people get pissed off.
I've had ton of gripes with the package through the years (can't remember how many times i've asked for that damned ascii file support), but after looking around in 2013 at all the packages i've used/use, and there have been plenty of them, i still think xsi is the only app that managed to put a smile on my face while working with it. There's something soothing about its workflow that just makes life in front of the screen easier.
Unfortunately we've all seen the writing on the wall the moment autodesk bought it.