Firefox Troubles

Hi, all!

I just got a new laptop (a Toshiba Satellite L675) today and I installed Ubuntu 10.04 on it with dual-boot. The only web browser I have on it is Firefox, since that's what came on the CD and I can't get online with Ubuntu to download another browser. As for hardware, the wireless thing on my computer is a Realtek RTL8191SE Wireless LAN 802.11n PCI-E NIC.

I'm trying to connect to the Internet using a public wi-fi network. My computer is detecting and connecting to the network just fine. However, when I open Firefox, it won't load any webpages. It gives me one of those messages that says "server not found." I looked at all of my Preferences and stuff. I don't have "Work Offline" selected, and I have Wireless Networking and Enable Connections enabled, and I'm not using a proxy. And as far as I know, I don't have any firewalls set up.

Also, at home, Ubuntu won't detect my home wireless network, so I can't connect there, either. At home, it's detecting all of the surrounding wireless networks, but not mine.

I looked at the Ubuntu Help thing about wireless troubleshooting and tried that command "sudo lshw -C network." An output came out, but I didn't see the words "Claimed," "Unclaimed," "Enabled," or "Disabled," as the Help document said should show up.

Also, just a note-- for the same networks (both the public network and my home network), I'm having no trouble connecting to it in Windows 7 and browsing the internet.

I don't have a clue what I'm supposed to do. I don't want to go back to using Windows if I can't get online with Ubuntu on this computer.

Any help would be greatly appreciated!