Vista - Vista Laptop cannot browse on Internet

Hi,
My Vista Laptop cannot browse once connected to the internet. This means I cannot update my internet security systems nor my anti-virus software.
I tried to search for other users having the same problem in your Forums, and found this thread..."On Wed, 12 Mar 2008 00:59:00 -0700, Paulski311
<Paulski311@xxxxxx> wrote:" In addition, I've now removed Norton 360, disabled the firewall, but the situation has not changed.

"Paulski311", had exactly the same problem I'm now experieincing. That is, at work, the laptop connects to the internet and browsing multiple sites at the same time is fast and efficient. However, at home, connected to my switch (5 port ethernet), I have no such joy. At home, connected to the same switch, I have two other PC's running Xp, that have no problem connecting to the internet. The ethernet connection shows "Access to Local and Internet" and the ethernet diagnostic reports no problems! I'd love to know from Paulski311 what he did to resolve his problem or ask any of you out there if you can help me?
Thanks
Gary

Please fill out your computer spec in your profile or post here please.

Hi Mansrm,
Thanks for the prompt reply. I've filled out my details, relevant to what I thought could be of assistance.
Thanks

How are you connecting to the internet just cable or through a router.

The set-up here is not unique, but is rather "simple". The main phone plug is connected to a duo phone port - that being a phone jack and a ADSL plug combined. The phone is connected off the phone jack and the ADSL line runs to a USB "modem" (Speedtouch 330). The modem than has a line which plugs into a usb port in the PC.
The pc has OS = Xp. The other PC's (all Xp, except the laptop - which is Vista) are connected to a 5 port - DES 100 5, Data link switch. As I said, the Xp machines all run smoothly and read the internet, skype, etc. The Laptop - No Go!
Help!