I'm pretty sure that for just USB mice, just usb and mousedev are necessary, but putting them all in as modules can't hurt -- an usused module doesn't matter.
Also make sure that you're loading these modules at boot time: put them in /etc/modules.
USB by itself isn't a module; it needs to be aliased to either usb-ohci or usb-uhci. For the Dell I8k, you want the usb-uhci.
Alias the module by editing /etc/modutils/aliases, and put in
the following lines:
alias usb usb-uhci
post-install usb modprobe hid
Then run update-modules, and those aliases will get stuck in
your /etc/modules.conf. Don't just edit this file by hand; your
changes will get overwritten!
Got all that? Excellent. Reboot if you want, or just modprobe usb-uhci evdev mousedev keybdev, and continue!