To use Google Earth on a Windows PC, you must have at least the following:
Operating System: Windows 2000, Windows XP, Windows Vista
CPU: 500Mhz, Pentium 3
System Memory (RAM): 256MB minimum, 512MB recommended
Hard Disk: 400MB free space
Network Speed: 128 Kbits/sec
Graphics Card: 3D-capable with 16MB of VRAM
Screen: 1024x768, "16-bit High Color" screen
DirectX 9 (to run in Direct X mode)