Google chart shows which current systems play nice with Chrome OS
Fortunately for you, they've posted chart over at the Chromium OS developer site detailing which laptops, netbooks, and other systems have been tested. The chart currently includes about 20 machines, including several from netbook leaders ASUS and Acer - not too surprising, since that's exactly the type of device Chrome OS will ship on next year.
Only a handful of systems have full hardware (wifi/ethernet/touchpad/suspend and resume) support out-of-the-box. It also looks as though Atheros wireless NICs are preferred, so you may want to scrounge one from your scrap heap or pick one up on eBay if you plan on playing with early builds of Chrome OS.