Hal, why won't my Linux firewall relay DNS traffic properly?

I'm running Debian here as I post this Question, and iptables are compiled into the kernel. Packet forwarding is active and all the rules check out; I've even tried setting --policy = ACCEPT on the FORWARD chain, but even though hundreds of packets are getting to my Windows client, as shown by the network adapter's stats, IE cannot resolve a web page. Windows is using DHCP, and is successfully acquiring the IP address I offer it in dhcpd.conf. The same network settings on this Windows machine work fine when plugged directly to the router that's connected to the Debian machine now. So, what's missing?