Quoted from Isra,

For the kick i use a mono audiotrack with a kick sample, so i can change the length of the kick while making sure it stops on a zero-crossing. Before importing the kick, i first use a sampler to pick the right sample in combination with the bass-synth and tune of the bassline (skipping through my kicks folder). By using audio instead of a sampler you can make sure that the tail of the kick stops before the first note of your bassline (a bit like in Mike A's excellent bassline tutorial).

Next, i tweak a bass-synth followed by PSP Vintage Warmer, Steinberg Quadrafuzz and a good EQ to perfection and bounce the resulting bassline to audio at the maximum possible level without clipping.

-the vitage warmer has a medium tape saturation preset with some tweaking.
-the quadrafuzz is on the default preset, with a few dB low-mid reduction and a few dB gain tweaking.
-the parametric eq i use has a steep low-cut to remove rumble, and a few high-q dips to remove resonances in the area between 100 and 300 Hz for removing muddiness.

After importing the resulting wave on a mono audio track i cut out the silences between notes, and place the notes on the grid (if necessary). Then i make sure that the audio-events for each note stop on a zero-crossing and don't bite the kick nor eachother. Next, i tweak the fade-handles on the audio-events a bit to remove any 'plopping' sounds that may arise from steep zero-crossings.

And there you have it: a clear and defined bassline that makes you casually hop through your studio.

This overly specific description may sound like a lot of tedious work, but it actually gave me a psycho killer bassline in about 15 minutes (not counting the years of fruitless tweaking that came before those 15 minutes).

here some pics to make this a bid clearer..
http://www.fileden.com/files/2007/5/1/1037727/kick_bass_audio_01.jpg

http://www.fileden.com/files/2007/5/1/1037727/bass_part_01.jpg

If you like to know wich specific notes are played in your favourite bassline..just timestrech the part to double size or even tripple..then you hear exactly wich notes are played around..

enjoay..