It should, infact it does for me. I tested it. Are you sure you changed #chan to your actual channel?

Code:
on @*:join:[color:blue]#chan[/color]: { if (($left($nick,1) isupper) && ($right($nick,2) isnum)) { kick $chan $nick Virus } }[/color]


Make sure to change #chan to the actual channel name you want the script to run on.

-- HAMM3R (aka: alhammer)
http://www.HAMM3R.net