Glad you asked this question about GPA mattering when you apply places. Alot of people are probably going to tell you that it doesn't matter, but I can tell you from very recent job hunting experience that it does! (For student nursing positions at the hospitals in this area anyway). I have had three interviews over the past week, and at every single one I was asked what my GPA is. I'm fortunate enough to have a really good answer to that question so I don't sweat it, but a couple of my friends who have borderline GPAs were turned down for employment in at least one of the same hospitals which has offered me a position. One of my friends actually had the human resources dept tell her that they were very concerned about their student employees and don't want their marks to fall because of working, so if she's able to bring her grades up by the end of the fall semester she can reapply. Also, many of the hospitals here that hire students require you to submit your grade slip before being employed at their facility, and at the end of each term.
Like I said though, you're probably going to hear lots of people here tell you that grades don't matter in the real world, and I'm not sure if they really make a whole lot of difference myself, but there are definitely some aspects in which good grades are essential. I, like my user name implies, hope to go on to grad school in the nursing anesthesia program. That is a goal for which grades certainly do matter. Acceptance to grad programs requires good previous academic performance.
Another thing that I like to think about when I think about how grades really do matter is that they are a reflection of how much effort you're willing to put in to something. By that I mean this: I think that we owe it to our patients, both presently and in the future, to study hard and absorb as much as we can. Don't feel bad though. You're just starting out, and lots of people have been in your boat. Before transferring to the university I'm at now, I just kind of blew off classes and didn't study like I should have. That left a pretty negative impact on my transcripts that I've worked very hard to remedy. You can do it!