What VNC service would you recommend?
Solution 1:
I would recommend Ultra VNC, which now supports Windows Vista and has file transfers.
Solution 2:
if you're using Linux I'd highly recommend FreeNX. I've often found it a lot more responsive than VNC and it runs straight over SSH is secure and wouldn't require any additional ports.
Solution 3:
I recommend NoMachine, they have both free and pay versions. Only for Linux do. Lot's of bells and whistles, and it's awesome.
But if you're on Linux and on a LAN, X forwarding is pretty awesome too (ssh -X myuser@server).