Wow, man! It worked really well!
I think it's important to clarify people of what to check before saying it didn't work (That's what I needed to do before it worked fine):
1) Check if the the "also launch" feature on Settings directs to "FF7+.exe", not "FF7.exe" or "FF7_Launcher.exe";
2) Check is FF7Config's Sound tab is not blank (open it as ADMIN);
3) Don't forget to use the FF7DISC1 image;
4) Reinstall "ff7_opengl-0.8.1b". If there's a problem, it's not gonna work at all.
By the way, Kaldarasha do you think it might be possible to install Team Avalanche's GUI as well? I'd love to use its menu/dialogue box/transparent battle command interface with widescreen battle background. Sorry if I'm sounding repetitive with this request...