I don't know the Spyder4 Express setup (for one thing it's new) but I doubt that it has a robust way of dealing with the brightness of your monitor. Consumer monitors as a bunch tend to be considerably too bright for photo processing. You may not see this while you are doing the processing/developing of your photos, but the "test" will be when you have prints done -- if you look at your prints in good light (either daylight or a good bright internal light) will they be noticably dark?
Pay attention to how the calibration process handles screen brightness. If it doesn't seem to deal with it at all, then I would take the step of lowering your monitor brightness significantly. How much depends on the monitor -- the old (now dead) Samsung I used didn't take to well to this, so I ended up using it as a "second" monitor. But in general I'd try to lower it until the display is a bit better than "ugly", then maybe run the calibration again to get everything trying to be in "balance".
Then, do as Tim suggests and have some test prints done. Make sure you tell the lab "no automatic corrections"! Then, like I said, look at the prints in good light. As Tim says, your monitor will still likely come off "bright" due to the projected light coming through your photos, but your prints should not come across as "dark" when seen in good light!