Here are the system requirements:
Microsoft wrote:System requirements
Computer with a 233MHz processor or higher (Pentium processor recommended)
Windows Vista 32-bit
Windows Vista 64-bit
Windows XP 32-bit with Service Pack 2 or higher
Windows Server 2003 32-bit
Windows Server 2003 64-bit
Windows Vista - 512MB
Windows Vista Service Pack (SP1) - 512MB
Windows XP Service Pack 2 (SP2) - 64 MB
Windows XP Service Pack 3 (SP3) - 64 MB
Windows XP Professional x64 Edition - 128 MB
Windows Server 2003 Service Pack 2 (SP2) - 64 MB
Windows Server 2003 Service Pack 2 ia64 - 128 MB
Windows Server 2008 â€“ 512MB
CD-ROM drive (if installation is done from a CD-ROM).
(Internet Explorer 8 Beta is only available via download.)
Super VGA (800 x 600) or higher-resolution monitor with 256 colors.
Modem or Internet connection; Microsoft Mouse, Microsoft IntelliMouse, or compatible pointing device.
You can find IE8 beta 1 available for download here. It runs on all versions of Windows from XP and up, with both 32bit and 64bit versions.
I've just installed this myself, but so far I do like it. As part of an expanded setup wizard that appears the first time you run the browser, you can import your Firefox bookmarks and other data, which is quite handy (I'm not sure which other browsers this works for). It'll even detect your Firefox extensions and tell you if there are any similar addons for IE! Microsoft also claims to have made great strides in standards compliance which is also good news.
I'll post more here once I've had a chance to play with this some more.
Edit: De-stickied, 10/26/09 at 14:24.