According to today's situation if you do a diploma course you may join as an IT technician. ( Install s/w, repair h/w, printer installation and etc). If you do higher diploma+CCNA, then their will be more potential for you to join trainee network enigineer, system operator or support engineer.
As my friend told me now NIBM introduced Bsc in Computer Science degree program affiliated with UCD which is far OK for facing today's competition.
Anyway NIBM is better place for beginning your higher education and success of your future is depend on how you do things. NIBM will be not responsible for anything that will happen to your future !
Work hard for achieving targets is the key. Gud luck