So what you're saying is that you want two separate GUI sessions to a Windows machine, right? That requires that you have "Terminal Services" enabled, and that is going to require that you purchase Windows Server 2003. (Or Citrix, maybe, but it might require Server itself.) Microsoft has decided that having more than one person logged in at once is something that you have to pay a lot extra for, despite the fact that it' obviously feasible in XP Pro, since you can "switch users" and still leave the first user's programs running; it'd just need to display those. I don't know that Apple has any such thing at all; maybe on OSX Server, but that's more different from OSX than Server 2003 is from XP. Any Unix from the last 15 years can handle it with no problem.