As black seraph says, you can get most of the usefull stuff here on Sins own site.
Although, if you want to add units, ie make your own or whip up something from a show, eg Star Trek, you'll have to look elsewhere for a modeling program.
The one I'm using at the moment is a free program called XSI Mod Tools 6 and it's available for free fromthe official website.
Would you like some tutorial thread links as well?
There's one by Ezraeil and I'm also running a thread although it's not as far along as Ezraeils and uses a different method.
