4 GB free on your HDD (including the Source SDK Base) or 500 MB (if you already have the Source SDK Base)
Step 2: Source SDK
Open Steam, log in your account. Download the Source SDK Base (NOT the Orange Box version) under Tools in Steam.
Step 3: GES Installation
EXE: Install Goldeneye Source to your Steam directory, under SourceMods.
ZIP: Unzip gesource** to your Steam directory, under SourceMods.
The SourceMods folder is usually located under “SteamApps”:
C:\Program Files\Valve\Steam\SteamApps\SourceMods
C:\Program Files\Steam\SteamApps\SourceMods
=====Step 4: GES 1.1 Installation=====
Now, you are ready to install the Beta 1.1 patch.
=====Step 5: Restarting=====
Restart Steam when the installation is complete. Make sure you completely close the program and not just minimize it onto the taskbar! Goldeneye: Source should appear under your games menu.