Hi, after further research into driver
detective, I don't think it will be of any use for this sort of problem (and as it turns out it isn't free, although I thought it was).
When you say you've tried the Vista drivers
do you mean you've pointed Windows to the driver and it didn't like it or did you search Windows update and it couldn't find it? I'm sure you've done it correctly but just make sure after you click "Update Driver..." you click "Browse my computer for driver software" and then point it to where ever you unzipped the driver to.
I downloaded the drivers from Support and Downloads for Current and Discontinued products
if that's is of any use.
Also the support number for setting this up is (US) 1-877-466-8646. It might be worth a quick phone call to see what they say about it.
I think the long and short of this is there isn't a way to get this modem working with Windows 7 x64 using USB.
As I posted previously, probably the easiest way forward would be to buy an ethernet hub, I think you can get one for $10 off of Amazon and that would pretty much future proof your modem for any new devices or Operating Systems that you don't yet own.
I'm sorry I can't be of more help.