Well, I've basically just been playing around with ifconfig and netconfig for the last 12 hours
I obtained my dhcp info from windows (using ipconfig /all). There is a Network Setup Guide
for Slackware at that link.
During boot up make sure linux is recognizing your NIC. It should assign it to eth0. Once you see that it has (by typing ifconfig), it's just a matter of inputting the right into netconfig. Basically, with a dynamic-ip address assigned by DHCP all you need is the dhcp server.
Once I had that configured correctly I turned off the laptop, unplugged the cable modem, and waited like 2 minutes (isp's recommendations). I plugged the modem back in, let all of the green lights come on, and booted into linux. Logged in, typed startx, and lo-and-behold I was online!
It just takes time to get everything working right. Thing is to just not give up. If one thing doesn't work try something else.
Hope this helps!
EDIT: Fixed URL, didn't realize couldn't use html.