It is a basic need to calibrate your monitor (actually it's only a profiling but for the ease of understanding let's use both terms). How can you seriously start any editing if your monitor is not showing what the digital data represent? Most monitors are offered with settings good for work or gaming or movies. But this includes settings that are not helpful for picture editing (e.g. increased contrast, saturation, emphasizing on blue/black).
I use Spyder2 Pro, got it 2nd hand. Works nice. I noticed a slight blue shift compared to my previous profiling 2 months ago. You can also check Digital Darkroom here, lots of information also covering the profiling topic.
