For those lurkers that might land on Sectorgame BEFORE landing on HLP (and some traffic never does) here is how to get FreeSpace 2 installed.

First, you will need a copy of the game. Either find a boxed copy or download the GOG version: https://www.gog.com/game/freespace_2

Install it. If you have trouble installing it from the CD, try running in compatibility mode.
The GOG version should install fine, however.

Then, install FSO to enhance your game and make it extra shiny: http://www.fsoinstaller.com/

Now you're good to go, pretty much. It's as easy as that

Descent/Conflict FreeSpace

Although you can simply install the FreeSpace Port for FSOPEN, if you would prefer to play vanilla FS1 you can still obtain it from GOG: https://www.gog.com/game/freespace_expansion
The GOG version should contain a wrapper or some other fix that enables you to play it on a modern system.
Generally you might expect to have issues with the original CD version, though it is a Windows game so *should* run in compatibility mode.
Only the GOG version can support higher resolutions.

Knossos is rapidly becoming a much better choice than the FSO installer. It also has the advantage of allowing you to install Diaspora too.

Yeah I saw that before, nice to see it's already operational!