try XFRSDC01 , it's a sample pack produced by deadmau5 that will help you alot for the drums.
Big Fish Audio & Loopmasters have several house and trip-hop releases.
i don't know for synth, i only use samples for house and add little b-lines made with any synth that can do a square or sine.
Hey =]
Well for synths it all depends what your after sound wise,
If your looking for zappy edgey trancey saws etc, then go for Sylenth1
Albino3 is good for solid warm slightly edged basd noises and waveform alternations
For simple but hard dubstep and dnb bass synths try the free Vsti's by Itchy Dubz http://rapidshare.com/files/238614608/ITCHY_SYNTHS_-_OVERDOSE_SUITE.rar
As for samples,
Id recommend Drumsound and Basslins Smith, Mutekki Vengence, Urban Warfare etc
There are so many about its ridiculous lol
