I'm sure it's been discussed already... proper exposure is a combination of shutter speed + aperture + ISO
If you don't want blur, you need to keep the shutter speed pretty quick. 1/2s, 1/5s, 1/25s shutter speed = blurry but properly exposed picture. 1/100s, 1/200s = not blurry, but much darker picture. VR lens can allow you to be a little more shaky (and using a slower S value).
So if you used S (or Tv for Canon) on the PSAM dial and set a value, the brains of the camera will automatically adjust to the appropriate aperture to get the best shot; generally at night, it will use the largest aperture (smallest aperture number) possible for your lens (unless you are spot metering). What do you have left to control? ISO. If shutter speed + aperture is still too dark, bump up ISO. It will cost you in terms of increased noise in the picture.
Get a feel of what your camera is capable of... what its limits are and what settings generate the most acceptable image. Use a constantly moving object (i dunno... a fan of some sort) in a low light environment (not completely dark mind you, some light) and shoot it. Play with shutter speed and ISO. If no fan, just go out on a main street, or a pet. As a point of reference, i am in a room lit by a single ceiling light (60W i think) with a decorative glass thingy. I used A and set 3.5, ISO is 1600, matrix meter and the camera is thinking of using 1/8-1/50s shutter. It's not dark by any means, but it's not bright either. Using aperture 1.8, the camera thinks 1/20-1/250. Doesn't mean you should go grab fast lenses to achieve what you want because larger apertures have their own characteristics - mainly objects in front and/or behind the point of focus can get out of focus.
If you didn't already know, your camera does tell you if it thinks your image will be too dark, too bright or just right. The scale in the viewfinder -...0...+ will guide you.
On a plus side, Lightroom is able to clean up noise in photos if you shoot RAW. You lose a little bit of detail but really who looks at photos at 100% crop anyways.
edited for some clarity.