For the list of Windows Server 8 changes of interest to the IT Pro see: Windows 8 for the IT Pro: The New Plumbing

To test all this stuff out, you will probably want to use the Windows 7 hardware you currently have. This list is sourced from the blog post at: http://blogs.msdn.com/b/b8/archive/2011/09/13/experiencing-windows-8-touch-on-windows-7-hardware.aspx
listing machines that the touch-enabled features have been "tested" on, where "tested" = "works on my machine," and not "tested and supported by Microsoft,"
It is offered here so that early adopters can update it with additional hardware that runs the Windows 8 Developer Preview "on their machine".  Feel free to add to the list, it is the wiki way!

You can find forum threads from other early adopters on both hardware and software issues at http://social.msdn.microsoft.com/Forums/en-US/windowsdeveloperpreviewgeneral/threads . Find Windows 8 sample apps to run at: http://code.msdn.microsoft.com/windowsapps/Windows-Developer-Preview-6b53adbb

You can also use the Windows 7 boot from VHD fetaure to try out Windows 8. Here's a how to blog post: http://www.hanselman.com/blog/GuideToInstallingAndBootingWindows8DeveloperPreviewOffAVHDVirtualHardDisk.aspx. You may also want to check out Dual Boot Windows 8 from VHD using Windows Setup.
Windows 7 machines that run Windows 8 (Developer Preview):



3M

3M M2256PW

Acer

Acer Aspire 1420p (PDC)
Acer Aspire 1825PT
Acer Aspire 5738PG
Acer Aspire Z5610
Acer Iconia
Acer T230H
Acer W500

ASUS

ASUS EP 121
ASUS TCA70

Dell

Dell ST2220Tc
Dell Studio 1747
Dell Studio One
Dell SX2210T
Dell Inspiron 2305
Dell Inspiron Duo
Dell Latitude E6420
Dell Inspiron One 2305
Dell Latitude XT
Dell ST2220T
Dell Dimension E310
Dell XT2
Dell XPS L702x
Dell Inspiron 1720

ELO

Elo 1522L

EXO

EXOPC

Fujitsu

Fujitsu Lifebook T4310
Fujitsu Q550 Slate

HP

HP TouchSmart_IQ526t
HP Compaq L2105TM
HP EliteBook 2740P
HP Mini 5102
HP Pavilion_tx2000
HP Tablet 500
HP TouchSmart IQ500
HP Pavillion DV3T-2000
HP TouchSmart 610
HP TouchSmart TX2Z

Lenovo

Lenovo C320
Lenovo S10-3T
Lenovo ThinkPad T410S
Lenovo ThinkPad X201T
Lenovo ThinkPad X220T
Lenovo ThinkPad_X60
Lenovo Thinkpad X510
Lenovo X201
Lenovo IdeaCentre Q150

NEC

NEC MultiSync LCD175M

Planar

Planar PX2230MW

Samsung

Samsung Series 7 XE700T1A

Sony

 Sony V J series
Sony V L series
Sony VPCL113FX/B
Sony VPCL-218FW  

Toshiba

Toshiba Portege_M700
Toshiba Sattellite Har/Kar
Toshiba Satellite L25