If you must run XP to run hardware (think scanners) get Windows 7 Pro that has a virtual copy of XP and just set that up to do scanning. There are some other posts about how to change the TCP to increase security, but DO NOT use the virtual for internet.
You can use a virtual machine clone of the current system if you are upgrading, but that might not be within the licensing guidelines. If you are NOT upgrading but doing a full install (which you kind of have to do anyway from XP) I believe it would be legal to virtualize the current system. One reason NOT to do this is that there are so many links and the tendency is to use the familiar. You are probably better off just using the new virtual copy from Win 7 Pro.
Otherwise get Windows 8.1 and a either a program called Start8 or Classic Shell that brings back the beloved start menu and opens to the desktop. This makes Windows 8.1 equivalent to Windows 7.6 (or some other later iteration of Windows 7.)
That way you won't complain in about 6 years about them not supporting Windows 7. See this info sheet from microsoft
http://windows.microsoft.com/en-us/windows/lifecycle
