As long as you unroot correctly, with the complete method (flash s-on tool if you used unrevoked, then flash a PC36IMG.zip with the contents of a RUU), then absolutely any changes you made while rooted will be undone. You will have a stock ROM, which includes all sprint apps and the stock boot screen (and splash screen, if that's what you meant). All data you had will be wiped out. The phone will look as if it had never been rooted, and you did a factory reset.
