WorldWide Telescope system requirements

For PCs:

PC with Intel Core 2 Duo processor with 2 gigahertz (GHz) or faster, recommended 1 gigabyte (GB) of RAM; 2-GB RAM recommended
3-D accelerated card with 128 megabytes (MB) RAM; discrete graphics card with dedicated 256-MB VRAM recommended for higher performance
1 GB of available hard disk space; 10 GB recommended for off-line features and higher performance browsing
Super VGA (1024 x 768) or higher resolution monitor
Microsoft Mouse or compatible pointing and scrolling device
Microsoft® XP SP2 (minimum) , Windows® Vista® (recommended)
Microsoft® DirectX® version 9.0c or later and .NET Framework 2.0 or later
Required for some features; Internet connection at 56 Kbps or higher through either an Internet service provider (ISP) or a network. Internet access might require a separate fee to an ISP; local or long-distance telephone charges might also apply

For Macs:

A version of Microsoft Windows must be installed
Macintosh® with an Intel Core 2 Duo (2.2 GHz or faster) processor recommended
1 gigabyte (GB) of RAM; 2-GB RAM recommended
NVIDIA GeForce 8600M GT graphics card with 128-MB SDRAM or recommended
HFS+ hard disk format (also known as Mac OS® Extended or HFS Plus) and 10 GB of available hard disk space
1440 x 900 or higher-resolution monitor
Mouse or compatible pointing device
Mac OS® X version 10.2 (Jaguar) and Boot Camp; Mac OS X Leopard is recommended
Microsoft DirectX Runtime 9.0c or later and .NET Framework 2.0 or later
Required for some features; Internet connection at 56 Kbps or higher through either an Internet service provider (ISP) or a network. Internet access might require a separate fee to an ISP; local or long-distance telephone charges might also apply

More WorldWide Telescope coverage from Astronomy.com