Hi all
most of the problems you might have on older hardware is in finding a decent video driver -- the W7 X-64 version seems to work in 99% of cases or in getting the on board LAN to work in 64 bit mode - even if the other components are fine.
Logon to Intel (or AMD or your Mobo manufacturer site) and download the video accelerator driver for the chipset you are using (for example GMXXX).
For a server its probably fine to use a mobo with on board graphics.
I've actually tested W2008 server on an old laptop - although added extra RAM so the laptop is 4GB.
I had to download the Intel mobile graphics accelerator driver for chipset GM945 to get proper resolution - then it worked fine.
Nothing per se in W2008 will stop you using it on older hardware so long as its 64 Bit.
Note however some older built in LAN cards only work in 32 bit even though the rest of the computer will work in 64 bit mode -- Via velocity gigabit cards are often a problem here.
Get round this by using a USB==>LAN device (only around 5 USD) or use another external LAN / wireless card. On the Laptop I found an Express PCI LAN card that worked fine in 64 bit mode.
Note - the latest Widows 7 x-64 drivers will in nearly all cases work fine with the exception of a few really stubborn LAN cards - which won't work even when Windows reports driver installed and working correctly.
You'll see this by "Unidentified Network" connection and you won't be able to connect to the Internet. The only solution is to use another LAN device as I've pointed out above.
More modern hardware will be fine -- you don't need "specific" Server hardware for running W2008 server -- even a modest laptop will run it.
BTW if you do want to run W2008 in a "Home" type of environment you might be interested in making it behave more like a Workstation
Have a look at this link.
http://www.win2008workstation.com/
Cheers
jimbo