Inferno Release 1 is completely different from Alliance. Install them to two different mod directories.
For INFR1, download from the main site athttp://inferno.hard-light.net/R1.htm
You only need to download one of the single files and the SCP patch.
For INFA, download from the main site athttp://inferno.hard-light.net/SOL
You need to download Alliance Core, Music Files, Inferno Core, Inferno Effects. If you want you can download the HTL Pack.
Crap, JR beat me to it, with links.
Hey, wait a sec, shouldn't you should put Solar Wars in the same directory as INFR1, since it uses some of the models (don't count me on this just yet, I'm not sure myself)?