IMO, most of these courses are just a waste of your precious time and money. I've done a 3 year Software Engineering diploma from Aptech, and believe me the condition of such institutes is really pathetic. I've friends who did some of these courses from NIIT also, and the situation there is no good either. Most of them don't have proper and experienced faculty to impart you proper knowledge as they want to earn money. No one recognizes any of such Diploma courses except the ones recognized by the Government like DOEACC 'O', 'A' and 'B' level (in IT field), or the CDAC.
I'd suggest you just concentrate well in these two years, secure good marks in your XII boards, try getting admission in one of the good colleges in your region, and again concentrate on you graduation rather than indulging yourself in something else simultaneously. Believe me, it's really very hard to do things simultaneously. I tried doing it. While doing my Graduation (Honours in Geography), I got myself enrolled in the Software Engineering course from Aptech, and just ruined my graduation (both marks and the college life). Everyday when the college got over, my batch mates planned to hangout (as my college was near some tourist hotspots), I rushed to attend classes at my study centre. Though, this helped me gain the reputation of the most Tech Savvy guy in my Department (of Geography) and eventually the title of TECHNOCRAT in the Farewell, and even today after more than 3 years after completing my graduation, I'm approached to design the Poster and Magazine Cover for the Annual Fest and the Annual Magazine, but the cost I paid: Missed the most valuable college days and had a mediocre performance in both the Graduation as well as in the Software Engineering course.