My Wifi worked perfectly from install with Mandrake 10.1 on my home network (I'm using it right now), but I can't seem to get the settings to work with the wireless network at school, which requires a WEP key. I've been right-clicking on the network icon in the bottom-right menu and using that to change the settings, but either they're not sticking or they're not working correctly. I've read about other tools for confirguring wireless, but I can't find/use kwifimanager and drakroam just gives me a bunch of error messages. Is there any kind of graphical tool I can use to mess around with my settings until I find one that sticks? Are there any special tricks for connecting to secure networks?

Its good to learn command line instructions in linux as these frequently give better error/debugging messages as well as removing an additional application layer to the whole process of eradicating the problem. Basically its a three step process to connecting to a WEP-enabled network.
1. Set the key
2. set the ssid
3. get/set an IP address

Okay, I've got the first two down according to iwconfig, but shouldn't dhcpcd accomplish the third? For some reason or another it doesn't work... though dhcpcd doesn't return any errors.

Not necessarily. I use the alternate command
dhclient eth1
to get my IP address. Your interface may be wlan0 or whatever in ehich case replace the eth1.

Still no dice... it says "No DHCPOFFERS received. No working leases in persistent database - sleeping." Any ideas what the problem might be? Back when I had windows on this laptop it connected with no problem at all. iwconfig says I have the WEP key and ESSID configured properly and that's supposedly the only two things I need to connect to this network.

Then I'd try disabling WEP on your WLAN altogether, re-try connecting and if this works you know its a WEP issue.

Unfortunately, that's not an option as it's my college's network.