If you are going to use 2.6 you need to update your
kernel module utilities, otherwise you wont be
able to use ip(chains|tables), the new package is
here
http://www.kernel.org/pub/linux/utils/kernel/module-init-tools/after you install that, you should be able to use
usb and iptables, and oh by the way, you should
always check before you install a new kernel, the
requirements for running it ;]
/usr/src/linux/Documentation/Changes
currently contains that information. and yes usb
and iptables DO work. also about iptables,
ipchains and everything else, iptables and
are just userland commands, the kernel uses
netfilter to firewall, you can (i think) still
even use ipchains with 2.6, you just need to
load the compatibilty module (not that you
should be doing that)