Couch to 5K???

Ok, so I ran another mile last night and tonight. That puts my week's mileage up to about 4 miles (I really need to keep track better). I seem to be stuck at the one mile mark. Different things seem to go wrong at a mile-sometimes I'm too winded to continue, sometimes my leg muscles are screaming at me, and lately I feel nauseous and dizzy by the time I reach a mile. I am attributing the latter problem to the stifling heat we have down here in Georgia. It got over 100 degrees today, and it's only June! I do try to run late in the evenings, but the heat and humidity get to me. Anyway, I'm getting off subject here. The point is, I run a mile and then I can't go anymore.
So! I am considering jumping into the Couch to 5k program I have read about online. I wouldn't start at Week 1 because I'm definitely beyond that, but maybe somewhere around week four. I haven't made any decisions either way, because the plan offers a little bit more structure than I would like. However, that may be what I need to push myself forward.
On a side note---adopting the "barefoot" running style has been the best thing that I ever did! My knee hasn't bothered me once since I ditched those blasted running shoes. I experience muscle soreness, but my joints are absolutely fine. I would encourage anyone who experiences a lot of joint pain when they run to consider the benefits of barefoot running.