Despite the fact that the original Day of Defeat mod didn't appear until 2001 (and DoD 1.0 in 2003), it was a classic triumph for gameplay over graphics. It was powered the Half-Life engine: already 3 years old following Half-Life's release in 1998, and itself based on Quake technology licensed from id software.
Skip forward to 2005, and things have moved on substantially. Gone is the DirectX 8.0 generation of GeForce 3 / GeForce 4 class cards, and enter powerful DirectX 9.0 cards sporting enough grunt to handle high levels of FSAA and Anisotropic filtering. Video memory has leapt from 64MB to 256MB, allowing high resolutions textures and bonus eye candy such as HDR. Processor speeds and system RAM sizes (and speeds) have increased dramatically, allowing realistic physics to be simluated.
Take a look below to see how far things have move forward since the original game: (click for fullscreen versions)