Well, I fool around on bass...I can't say I actually play it.
But here are a few important things:
1.) The 4 strings on a bass are exactly the same as the bottom 4 strings on a guitar, only an octave lower.
2.) If you can play a riff on guitar using the bottom 4 strings, you can play the same riff on a bass.
3.) If you just play using tab, this doesn't apply...but bass music is written in bass clef, and while the scale is still the same (A to G)...the lines and spaces on the staff are not
Guitar:
----------------------------------F
E
----------------------------------D
C
----------------------------------B
A
----------------------------------G
F
----------------------------------E
Bass:
----------------------------------D
C
----------------------------------B
A
----------------------------------G
F
----------------------------------E
D
----------------------------------C
Here's a neat little trick...if you're looking at a piece of music and you want to convert bass clef to treble clef just take the note written (in this case I'll use a G in bass clef, as it's on the middle line of the bass clef staff) and move it downward 2 places (1 space and 1 line, or vice versa) and it now is a G in treble clef. To covert treble clef to bass clef written, just do the opposite.
Another thing to remember about music written for bass guitars...the note you hear is actually an octave below what is written (they do this so as to make it easier to read).
Now, as far as PLAYING bass guitar goes...as I said I just fool around...one of these days I may actually get serious about it. The basics of playing notes and scales isn't really that difficult...but don't expect to become Geddy Lee (aka "Bass God") in a few weeks.
Big Al 
AIM: BigAltheCrusher 
. But i been hearing that its easier to learn on an electric then a acoustic..does anyone know why? 
