Parallels for iPad works fine. Was a little latent compared to other products doing the same thing. I like Splashtop Whiteboard better. Splashtop is only $9.99 and the Whiteboard addition is $19.95. Parallels is $79.00 a year as it looks like it connects through one of their servers to talk to your computers from anywhere. Not sure this is necessary.
Good article about Parallels from Mashable.