I downloaded the Fallout 2 installer, but when I try to open the exe, it tells me I need another program to use it, what excactly am I supposed to do?

Try downloading it again? Might we have a screenshot of said problem?

I'm not sure if they'll be of any help, but here are some screenshots. They show me going through the process to start the install, and the third shows why i can't get it to work. The third one shows the GOG downloader because I tried to use that, but I can't log in to it anyway for some reason. I'm re-downloading it at the moment to see if it'll work, just in case.

So, did you use the downloader or did you just download it?

I just downloaded it through Firefox, the downloader doesn't work for me because I can't log in to it.

Alright, I'll let you know how it goes when I'm done.
*UPDATE* After a second download, everything worked out. Thanks for your help.

No problem.