No problem to shut it down, but as the other fellers say, turning it off depends how old the PC is. I've got an ancient Pentium I acting as a backup/file server and running the excellent FreeNAS -
http://www.freenas.org/ - network attached storage mini-OS. I can shut it down over the network but I can't turn it off - irritating. If you're a tinkerer, a 12v/240v relay and a bit of bell-wire will do it - with a bit of ingenuity you can get it to boot when your main PC is turned on.
As regards VNC, just recall that VNC isn't very secure. It requires a password when a viewer tries to connect to a server and this password is encrypted to deter snooping, but the following graphical data, the VNC protocol, is not. In other words, if you are using VNC across the Internet without some sort of tunnel (SSH, IPSEC, PPTP), you are exposing your data and information to the world. But this doesn't sound like an issue for you here.
I think Putty -
http://www.chiark.greenend.org.uk/~sgtatham/putty/ -is a pretty good free Telnet/SSH client.
copSSH is a free ssh server and client implementation for windows systems that I haven't used, but looks neat -
http://www.itefix.no/phpws/index.php...position=22:22
PS: Tunnelier -
http://www.bitvise.com/tunnelier - looks interesting