Good luck to all participants.

Will be sent as a gift through Steam.

Directly from Wikipedia:
Half-Life: Source is a straight port, lacking any new content or the Blue Shift High Definition pack. However, it does take advantage of vertex and pixel shaders for more realistic water effects, as well as Half-Life 2's realistic physics engine. They also added several other features from Half-Life 2, including improved dynamic lightmaps, vertex maps, ragdolls, and a shadowmap system with cleaner, higher resolution, specular texture and normal maps, as well as utilization of the render-to-texture soft shadows found in Half-Life 2's Source engine, along with 3D skybox replacements in place of the old 16-bit color prerendered bitmap skies. The Half-Life port possesses many of the Source engine's graphical strengths as well as control weaknesses that have been noted in the Source engine.

TL, DR: Graphics-wise, better than Half-Life, but still worse than Half-Life 2.