Is the local copy of IE the correct build for NT? You can not stick a copy of IE thats for WIn9x on an NT box.
Any modem should work, don't put too much trust into the 'specs' of hardware. But at the same time, if it is a host dependant type modem, such as the "Plug N Play' or "Designed for WIndows" modems, you do need some horsepower. But remember that a modem should not need a 500Mhz machine to turn it over. I've run 56k modems on 133Mhz machine with no problems at all.
The requirements sometimes relate to the bundled software and not the hardware requirements.
The best way to determine if the modem will work is by installing and running it.