Cheers man, starting to make a bit more sense :) Is there much difference in quality of these two types of sub?
Something else i'm not gettin, if i had a 2 channel amp would that just power a sub and if i wanted other speakers i would need a 4 channel one?
Also are front components powered from the head unit or is an amplifier needed?

your front components (which is just a posh way of saying your front speakers) are powered off your head unit as is standard from the factory, when people want to up their systems they tend to run them off an amp to give them more power/clarity. this will mean having to rewire them in from the boot or under the seat where ever you choose to put the amp (sounds harder than it actually is )

As for the channels bud you could run 2 subs off a 2channel amp or your components as there is 2 channels but if you only want to run 1 sub then what you do is bridge the channels this then gives the amps full power to the 1 sub

The difference between the active sub and non active is that the active 1s tend not to be overly powerfull but will give a good amount of bass if your only going for a light system on a budget,

if i was to pick on a budget of £200 i would go for

this is an active sub with wiring kit, i fitted 1 of these to a mates car and was very suprised with how good it was for the money
link
A head unit like this ( just using this as an example your choice entirely )
link
and then you should be left with enough to get some cheap components like
these or these

thats a total of £179.96 with the ground zero comps or £190.97 with the vibe edge comps

remember quality is compromised when shopping really cheap, the vibe edge stuff tends to be a good starting basis from what ive gathered

That edge stuff is awfull mate. Over-rated figures, cheap components, chinese built, poorly build boxes.

The ported boxes are tuned to 70hz!! This isnt really bass in my opinion! My front components play down to 80hz! For music its best to tune somewhere between 30 and 40hz.

I think your best bet would be to get some components installed first, but definitely run them off a 2 channel amp! You might be happy with them and find you dont need a sub.

Ok its all becoming much clearer now thanks guys, and cheers for clearing that up rorz :y:
I think i will do that Coonper, get the front components first and see how that sounds.
Do they sound alot better when run off an amp? or is there not much in it?