Please see http://www.hard-light.net/forums/index.php/topic,44569.0.html

The gesture is appreciated, but it's not a proper solution. It looks like you've come up with an updated version of ShivanSPS's pack, but it doesn't really make the install any easier, and it also makes things worse by adding individual files outside of the official MediaVPs and Releases. Things like Nebulae and the shockwave graphic need to be a part of the official media release. It's a nice, fast, short-term fix, true. But it's going to cause complete chaos when all of the official files are upgraded to the next version, but everyone using your pack is still seeing the old effects. And it will be a tech support nightmare to fix because of all the standalone files scattered throughout the install, people will either have to hunt down and delete each one, or do a clean install of the new SCP version.
However, if you can get away with hosting 650MB files, you could definitely host a mirror.

What's your webspace situation?
To me it looks like the best method to hammer out an easy install process is to use:
1) [DW]-Hunter's Freespace 2 Installer
2) Turey's FS2Open Installer, upgraded
3) Launcher config guide
Unfortunately this leaves Mac and Linux users high and dry, so it might be worth it to have a separate Step 1 download that contains the FS2 directory (in a .rar file). But it does allow everyone who has Freespace 2 installed to start at Step 2 and use the same process as everyone else.
@Turey: Does Java possess the OS awareness to generate shortcuts/symlinks for the various platforms, and is it possible to provide a native binary for each one (in case they don't have Java installed)?