Yes, it can run GMOD.
Yes, it can run GMOD.
He might be able to run GMOD on a low setting with his specs. A Core 2 Duo and 4GB RAM are decent for older games, but performance will depend on how he sets it up.
I recall playing Gmod on my Intel Atom 270N with 2GB RAM and Intel GMA 950. Likely it worked, though you shouldn’t expect very high resolutions.
OS: Windows® Vista/XP CPU: 1.8 GHz RAM: 2 GB Memory: Graphics: DirectX® 9 level Card (needs SSE support) DirectX: Version 9.0c Network: Broadband connection Storage: 5 GB free space Sound Card: DirectX® 9 compatible Notes: Mouse, Keyboard, Monitor