I could find no support information from HP for Win7 on that unit.
It does however have a space for a "full size" graphics card.
Here are the two places I found specs from HP, note that the second link is for windows OS certification, since it is a server, there is little to no reason for HP to test (or support) a non-server OS.http://h18004.www1.hp.com/products/quickspecs/12476_na/12476_na.htmlhttp://h18004.www1.hp.com/products/servers/windows/index.html
A little deeper, I found this list of MS OS's supported for that unit.
"Microsoft Windows 2000
Microsoft Windows Server 2003
Microsoft Windows Server 2003 for 64-bit Extended Systems
Microsoft Windows Server 2008 Essential Business
Microsoft Windows Server 2008 R2
Microsoft Windows Server 2008 Small Business
Microsoft Windows Server 2008 W32
Microsoft Windows Server 2008 x64"
And then later this statement - don't know if that is applicable to your purchase though.
"NOTE: ProLiant DL servers no longer ship standard with NEMA power cords (187335-001) that allow connection to 110V US wall outlets in a home or office. ProLiant DL servers are primarily connected to PDU's in data center racks so they now ship standard with only a PDU power cord (416151-B21). If a user wishes to power a ProLiant DL server using a 110V receptacle (NEMA-15), the above NEMA power cord must be ordered separately."
While I am sure I have seen "servers" that are certified for Win7, this does not appear to be one.