>I need to be able to view a PC remotely. From any location and from various PCs running various operating systems. The box I need access to is running XP Pro. I'm unable to always load software on the other PCs/Laptops that would need access to this box. What is the simplest solution?

If you can't use Remote desktop, GoToMyPC is a viable alternative. It is hosted (yeah - you gotta pay for it), but it works well.