Where can I put my money that won't make me angry?

Ok, so I'm reviving an old thread because my bank keeps recommending ISA's to me. Do I want one? Is it different from a savings account?
I am balancing a fine financial rope at them moment where I am still automatically putting a small amount of money (£15 per week) into my savings account even though I am heavily into my overdraft.

Is transferring the bulk of that money (a couple hundred pounds) into an ISA a good idea?

I'm in exactly the same situation and pondering what to do... i'm with Lloyds and they keep thrusting new savings accounts at me all the time. I save regularly but I have no idea which is the best and I'm well into my overdraft too... :s