What version of windows 7 should I buy?

I recently built a new desktop tower and I am trying to figure out which version on windows 7 I should get?
I have a network printer and will be using a wireless/wired network in my HOME. I will also have a all in one inkjet printer connected directly to the desktop that I would like to have the option to use it as a shared network printer.
I have some programs that might not be compatible with 7 I am not 100% sure on this but I just want to make sure my older (maybe 5 year old) programs will work.
The hardware on my computer will for sure run Windows 7. I am not worried about 7 not running. Since this is a computer I built. In the future I maybe upgrading components that may require a reinstall of windows 7. I would like to be able to reinstall windows 7 to the desktop if I need to without having to buy another key activation. I only plan on using windows 7 on this desktop. I know I want a 64 bit version of Windows 7. At this time I don't see the need of connecting to work domains. I would like to be able to use VNC to be able to work remotely computers on my home network which will also allow me to monitor what my children are doing on the computers they are working on. I will be using this desktop mainly as a home network server a place where I keep backups, for pictures, home videos, among other files. I will however more than likely keep these files on an external hard drive attached to the desktop. Could I buy the family pack Windows 7 and be able to do a brand new install from that for the desktop and upgrade my laptop from Vista Home Basic 32bit and possibly upgrade another machine of mine. I am just not sure with all of the Versions which one would be my best fit and then I have to consider OEM, FULL, Retail, and upgrade. Can someone please help me in making a good decision?

I am not familiar with doing install from an image. Could you briefly explain that process? Is there a program required to do this? Thank you for the help.

Wolves,
I am looking at the 3 license pack as another option. To upgrade my laptop and to do a new/clean install of windows 7 of my recent desktop build. Also to possibly upgrade another machine I have. I can put up with Vista on my laptop even though after using my wife's laptop I think I would really like windows 7. Just a matter of making a decision. My main concern with the Family pack of windows 7 home premium is since it is technically a upgrade. Can this software pack do clean or new install on a newly built PC?

How well would file share and printer share work across my network if all of the PC's are not Windows 7? Currently I have one laptop running vista home basic, another laptop running windows 7 home premium, desktop running Xp pro svc pk2 (Thinking this computer will go away since it is old and slow or be the kids computer), the new desktop that I built that will run windows 7 probably home premium, and one more older desktop (previous home built) that I am going to install linux on to try and learn about that OS. If the vista laptop and the new desktop running windows 7 home premium will communicate (play nice) across the network and allow me to use VNC between the machines. I think I will just get the single license copy of windows 7 home Premium. Since with the computers I have I would be not be using the 3rd license available in the family pack and I am not planning on adding another windows machine to the family. (Sorry thinking/rambling) However with the family pack 3 license I could upgrade the vista laptop to windows 7 and do the clean install on the desktop and just not use the 3rd license or hold on to it in case I add a machine to the network. That would make all of my machines windows 7 home premium and I would still have a license to use if I wanted. That should eliminate any network compatibility issues if all of my windows machines were the same version of windows 7. Does any of my rambling make sense? What are your suggestions? Since clean installs are possible with the Family pack upgrade that opens options up to me.