This will launch Remote Desktop for all of the servers, but you still have to input credentials. There are ways you can implement Single Sign On but it only applies to Windows 2008 and 2008 R2. mstsc doesn't have any switches for username or password, so it can't be scripted. There isn't even a hack for it since you can't use sendkeys to a remote desktop window.
Create a file with server names one per line and put it in the same directory as the batch file.
Create the following batch file
@echo off
setlocal
cd /d %~dp0
set file=Servers.txt
for /f %%a in (%file%) do (
echo mstsc /v:%%a
)
Remove the echo to actually launch Remote Desktop. At least it takes 1 step out of the equation and you can always save your credentials so it doesn't prompt for them which is more secure than putting them in a file.