Puoi usare ssh per spegnerla da Linux. Io per il mio serverino domestico faccio così (ce l'ho sotto la scrivania, ma non ha tastiera né mouse):

codice:
ale@debianix:~$ ssh pingu@192.168.1.5
Password:
Linux debserver 2.6.18-4-686 #1 SMP Wed Feb 21 16:06:54 UTC 2007 i686

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
No mail.
Last login: Sat Mar  3 00:18:14 2007 from 192.168.0.3

pingu@debserver:~$ su
Password:
debserver:/home/pingu# shutdown -h now

Broadcast message from root@debserver (pts/0) (Sat Mar  3 12:09:38 2007):

The system is going down for system halt NOW!
Da Windows credo tu possa fare praticamente la stessa cosa con putty (http://www.chiark.greenend.org.uk/~sgtatham/putty/)

Non so invece come sia possibile accenderlo.

.a.