Appreciate the sentiment of wanting to protect yourself and your loved ones, but if you do go down this route, make sure you do it right. Know the laws, take a class on how to use your weapon, know when to draw one and when not to. A friend of mine likes Armed Citizens Legal Defense Network, which regularly shares interviews with lawyers and police. There's a lot of discussion about local laws, how different situations tend to look when played back to a jury, etc. (i.e. knives tend to take a surprising number of stabs to take down an assailant, most untrained individuals see 15 punctures and instantly jump to excessive use of force) If you do decide on a gun, think about if you want a concealed carry license. Others here have talked about shotguns and rifles too. In your situation, you might want something your girlfriend can grab if you decide to leave it at home. (Or both carry) Separate from a weapon, also see if you can do anything about your home security. If you can, also try talking to your landlord and seeing about installing a better lock / guards on your doors / windows so any punk can't kick your door down. Advice out. Godspeed.
Advice appreciated. I'm actually set to move out of my apartment to another city in about five weeks, so I'll be looking into portable security systems, and you can be sure that I'll have webcams on a home LAN with a loud-ass siren. But I'm still getting a gun. Most of my friends have some good weaponry, so it'll be nice to go shooting with them, as I spent a lot of my childhood hunting, shooting skeet, and around a lot of guns in general.
I'm not really sold on webcams or CCTV for security. They can help legally, post-break-in, but less so in the immediate moment of a threat. If it's a choice, I'd personally put my money on stronger entries and decent lighting... Talking to your neighbors can help too if you know the person's appearance.
I'm stuck renting places for another 4+ years, but when I'm done, I'll build a house.