I usually use a Supernova for my synth leads, and I must admit I'll always take the easy route and find a good preset first, but I do try and manipulate into something not remotely resembling the original sound.

Recently gettin into fm synth sounds, they're great for that metallic grinding sound. Try www.oxesoft.com for a free fm synth, and also Native Instruments FM7 does a good job apparently.

Just mangle stuff until u get what u like the sound of basically! ;)

Effects, just go crazy, I always use a bit of delay, and possibly some phasing/flanging (Waves Metaflanger and Enigma are good for this). Distortion aswell (not too much tho). And recording the synth to an audio file in the sequencer and minimising the sound with eq so u only hear the frequency range u need to give the sound it's character gives a professional sound.