Where I got this from: Discord desktop app on Windows XP
How to do this?
Step 1. Download Discord from https://dl.discordapp.net/apps/win/0.0.309/DiscordSetup.exe
Step 2. Extract the setup using 7-zip
Step 3. Extract the nupkg using 7-zip
Step 3. Go to Discord-0.0.309-full\lib\net45
Step 4. Send Discord.exe to your desktop as a shortcut
Done!