Hmm..., the Lexmark drivers for Vista should work fine for that Vista computer, however I have known of some people to have some issue with networking devices like printers between Vista and XP machines; and yes, they're pretty knowledgable people. If the computers are near each other, than you can just get a USB peripheral switch/splitter; otherwise, which computer is this printer shared on? If it's shared on the XP machine you may have more luck than the other way around since the extra security crap on Vista may be interfering with sharing the printer over the network to other computers...