InfoPath Dev

Hi,

I have a SP2010 list with an Infopath form. On this form I have a people picker field which allows the user to enter multiple selections. I'd like to extract the username for each user from this field removing any of the domain information etc. So instead of Contoso\JoeBloggs I'd just have Joe Bloggs, but this needs to be done for each entry in the box, so

Contoso\JoeBloggs; Contoso\AnnOther; Contoso\WilliamGates

becomes

JoeBloggs; AnnOther; WilliamGates

Any idea how to make this work with formulas? 

Thanks 

Failing this, does anyone know a way of identifying whether the username of the user opening the form can be used to "scan" a people picker field with multiple entries to see if their username appears in the field? I want the form to switch to a certain view if the username exists in the list of users in the people picker field and if it doesn't then the form switches to a read only view.

EDIT - The contains, doesn't seem to work for this, even if I write the list of users from the people picker into a text field.