The setup is relatively straight forward, although a little lengthy. The
instructions described here is for windows vista home premium only.

Setup: Linksys router, Windows Vista Home premium, Trend Micro
firewall/antivirus

1. Setup the the PPTP VPN server in Vista. This involves setting up a new
incoming VPN connection and assigning IP addresses for incoming
connections.

Instructions for Vista:

http://theillustratednetwork.mvps.org/Vista/PPTP/PPTPVPN.html

for XP inst: http://www.computernetworkinghelp.com/content/view/41/1/1/2/

2. Setup my linksys router's firewall (I could get to it by opening a
browser and visiting http://192.168.1.1. This is probably dependent on your
router. You need to allow PPTP tunneling and setup PPTP port forwarding to
the IP you setup in step #1

(Note that in the link I forwarded, the router firewall setup instructions
mistakenly setup port forwarding for 192.168.11.11 instead of
192.168.11.31)

3. Additionally I had to enable the incoming traffic on PPTP port (1723) in
my Trend PC Cilin firewall.

4. Lookup the external IP address of your router from the router's admin
page. I got this off of the "Status" page from router's admin interface
(http://192.168.1.1)

5. Setup the PPTP VPN connection from the iPhone. You need to enter the
external IP address of your router. Remember to enter the name of your
computer under "Description". Also, set the encryption level to "Auto" and
Send all traffic to "off".

You should be all set to connect to the VPN, fire away ezShare and access
your files..