Internet dropouts

Hi all,
I'm turning to IT forums in desperation, as there seems to be little help available from the people who are supposed to be providing internet support locally...

I have recently switched from a landline broadband connection that I had connected to a wireless router (which was working perfectly) to Optus wireless broadband using a USB modem (HUAWEI mobile connect 3G modem)... and now, although my connection to my wireless service is great, my internet connectivity keeps dropping out. Like, all the time. Right in the middle of important things, like banking etc.

I have been trying different settings on internet explorer, which doesn't seem to help, and I've looked in a bunch of other areas for wireless settings - but as I'm not a computer expert, i really don't know what they do 9so I'm afraid I might do something terminal to my laptop). I read another post about wireless internet dropping out, and thought there may be someone out there who knows about this problem...?

My HP laptop currently uses an Intel(R) PRO/wireless 3945ABG network connection, and I'm wondering whether there is something conflicting in the settings here that is causing an issue...

Anyway, if anyone has had a similar problem and knows a fix, Id be forever grateful

cheers and thanks,
Monique