This is a question we are asked regularly here at LEDStop, unfortunately the answer is complicated we will try to explain why below..
Traditional Dimmer Switches (Leading Edge)
These switches use what is called 'leading edge' technology, they work by reducing the A/C cycle at the beginning of the electricity waveform and they are designed to deal with the higher wattages used by traditional lamps, typically loads of 250W/400W/1000W. The traditional switch will need a minimum of a 10% load to operate correctly which is fine for a circuit of 4 x 50w lamps using a combined output of 200w but not ideal for the LED equivalent which will use just 24 Watts.
Although it is entirely possible you're traditional switch may work we definitely recommend using an LED Dimmer switch, if you start to experience flickering or strobing on your LED lights combined with a traditional switch you should stop using the LED lamps immediately as this will shorten their lifespan considerably (maybe 6 months) and you will not be eligible for a manufacturer refund.
LED Dimmer Switches (Trailing Edge)
Dimmer switches designed to work with LED technology differ from tradtional switches as they work by reducing the A/C cycle at the end of the electricity waveform, although it sounds simple the technology used to achieve this is far more complicated which is the reason why LED Dimmers are more expensive than their traditional counterpart.
Currently LED Dimmers are still being produced to handle the same loads of traditional switches which is why we recommend always loading each circuit with enough lights to match at least 10% of the dimmers switches load.
For example if you were using a 1 Gang Varilight V-Pro (250W Load), You will need at least 5 x Megaman 6W GU10 LED lamps to achieve a consistant dimming range.
Megaman have supplied a light of there approved dimmer switches here
The situation is not perfect at the moment but we believe more manufacturers will be releasing trailing edge dimmers with lower capacitive loads to deal with the growing LED market shortly.
We supply only LED compatible dimmer switches available here, if you have any questions on an LED project you are working feel free to get in touch here.