VB File to change file files with extension .rmt and and donot strart with era*

Hello, I need help with writing a script to run in c:\Test folder to look for files with extension ".rmt". If the file name does not start with "era*" I want to rename the file so that it starts with "era" Plus original file name. If it is not possible to have the original file name then I want to have the name "era" followed by the sequential number 1, 2, 3 etc.
Can someone help me out?
Thanks in advance.