At my daughter's school here on Crete, we have a desktop and 3 laptops each running XP Home in English. We have genuine authorised software on all machines mainly Office 2003 and educational software supplied by publishers of learning schemes. Some software is 2 or 3 years old. The laptops are sometimes networked to the desktop wirelessly for file sharing and emailing and internet access. One laptop has been stolen and needs to be replaced. Replacements tend to come with Windows 7 pre-installed. Do you see any problems we may have if one laptop is running 7 & all other computers are running XP. Alternatively, what is the cheapest way to upgrade a desktop and two laptops to Windows 7? All purchases of Windows & laptop will be done in England & I have a tame IT bod who will shop for me in return for free accomodation for his holiday here in this glorious island.