I am trying to make a synthesised sound thats kindof sounds like a guitar/vocoded synth that is currently present in this track by Fedde Le Grand from 1 minute 32. It kinda sounds like something Daft Punk would also use.
To me, that "guitar" sound seems fairly close to a square wave - maybe a saw that has been heavily low-pass filtered with little or no resonance and then heavily distorted. The "vocoder" sound you are hearing is probably just a vowel / formant filter. If you don't have a formant filter, you can use parallel bandpass filters to accomplish the same thing.
Distortion is a big part of the electric guitar sound. The problem guitar players have is that a plucked string decays quickly. If you want your note to last longer, you amp it way up. This causes the characteristic distortion that we associate with electric guitars, but it also takes longer for the massively amplified signal to decay past the clipping point. During that time, it sounds like the note is being held, when it is actually decaying before the amp.
If you want something more guitar-like, try Karplus-Strong synthesis. You can get a decent guitar sound by sending a very short click or burst of noise through a delay that is between 1 and 50ms. Adjust the length of the delay to tune the "string". Turn up the feedback of your delay (probably 80%-99%) to get a realistic note. Note that you will still have the same problem that players of real guitars have with sustain.
You can get this exact sound from various digital effects pedals - my Line6 HD500 and an earlier Zoom 9000 both had presets that could do this.
You need a noise gate and compressor - to give you a sharp attack and then keep the signal gain at a high level until you stop the note. Once you have that envelope shaping, you can use whatever waveform you need, and as ObscureRobot suggests, a square wave will give quite a good synth noise.