rolling back modem driver

Hello and thanks for the great site.

I have a Fry's clone with xp home. Right out of the box, no matter what I
tried it would not connect higher than 28k (my old computer (clone AMD K2
with an older HSP 56) connects in the same connection at 46 to 50k) so I
decided to look for a newer driver. Device manager shows the modem as a PC
Tel HSP 56 MR (SIS) with driver provider as PCtel dated 11/25/2003
v.12.300.24.0. I couldn't find where PC Tel has any drivers but Conexant
makes the chip sets and they had a generic xp driver for HSP 56 mr. from
2004. The driver seems to have installed since now I get a popup that says
"no PCTel modem found-v.92 tray will close". It is working but still will
not connect higher than 28k so no improvement. I would like to roll back the
driver to the original one and try something else but have not been
successful since the install wizard cannot complete the install. No doubt,
I'm doing something wrong. If anyone knows where I can find instructions for
rolling back the driver made for ordinary people, I would be very
appreciative.

Thanks again,

Dan