It is a tough nut to crack since you have a conflict. That being more than
likely a kernel =/> 2.6.24 ( You can check by using uname -r). Ndiswrapper and
the kernel are trying to use the same device.
The support for the wireless card is built into the kernel since the above noted kernel.
First uninstall ndiswrapper, a howto:http://www.camsmac.com/unndis.html
Then you can either use the kernel module which I believe should start after
you remove ndiswrapper.
Or you can use the serial monkey installation:http://alien.slackbook.org/dokuwiki/doku.php?id=slackware:rt2xxx
As far as the 8139too There are two modules for that chipset since the device
changed. There were reported problems with both modules being available so
one of them iirc 8139 was blacklisted. You can change the blacklist iirc is is in