The first three games came out in 2007, 2010, and 2012. The first one is a little dated, but Mass Effect 2 and 3 still look and feel quite modern.
If you don't want to deal with some out-of-date graphics and gameplay decisions, I'd advise you to just jump into ME2. It's also the one that most people think is the best. But ME1 is a great game with a great story, and it might still be my favorite, so if you can handle it, it's still worth a shot.