Dell Inspiron 1501 Problems wifi/ upgrading

Dell Inspiron 1501 Problems wifi/ upgrading

I recently installed Ubuntu 11.04 on an Inspiron 1501 with an AMD Sempron.
I think the RAM is probably low because it is very slow. Googling the
problem, I noticed that a problem with the coding in Dells shuts off the
wifi card.
The solution seems to be to input this code.
sudo apt-get remove --purge bcmwl-kernel-source sudo apt-get install
linux-firmware-nonfree
However, once I did that, it made the wifi settings visible, but still not
accessible. Before enter the code, you couldn't even see the words. Now it
says WIRELESS NETWORKS and Device Not Ready (Firmaware Missing).
If the solution is to update Ubuntu, then that leads to my next problem. I
can't install any additional software on it. I go through the Software
Center, but as I try to install, it says the following:
Failed to Download Repository Information.
I am not an IT guy. Please help if you can.