I dont really get it, I have put Regular XP Machines (no updates, not even SP1) on straight internet (no protection at all) and have not had a problem nearly that fast...
UPDATE:
I think I might try doing this sometime, just put a brand new machine on the net and see what it does...
Also, Active Ports is a pretty cool program, take a look at it here:
http://www.download.com/3000-2085-10...age&tag=button