You didn't mention the capacity of your current battery. Perhaps it's weak or worn out. Why not just buy two or more "extended size" batteries and an external charger? It does appear that this laptop runs on 11.1 volts which could allow you to make your own power source from, perhaps, UPS batteries but that would take some creativity and have some risks. As well, bigger power sources would make the laptop less portable.
Basically I'm looking for a fair cheap way to use my laptop without having to have it plugged in all the time. Isn't that the point of a laptop? To be wireless? I'm currently running on a Dell Inspiron 1520 Laptop. It's almost a year old. When I'm surfing the net and it is unplugged from the power source I have basically an hour tops. Which I think is pretty pathetic. I've done some research on buying an external power source to boost the power while it is unplugged and the basically run $100-150, but the reviews are basically hit and miss from amazon to other sites. So I'm just wondering if anyone has had some really good good luck with an external battery that could boost the laptop power to last more than just an hour unplugged. If anyone has any suggestions I would be more than happy to hear them.