You could setup a Virtual Private Network (VPN) or a Secure Shell (SSH)
connection... Both methods are encrypted, safe and secure...Important
points, IMHO...

I use OpenVPN (free) which is one option... This method uses a cert and a
key file which is protected by a strong password...

http://theillustratednetwork.mvps.org/OpenVPN/OpenVPN.html

http://www.sbeattyconsulting.com/blog/index.php?p=3

SSH (free) and either WinSCP (free) or WebDrive ($$$$)... Use a strong
password or a private/public key pair protected by a strong password...

http://www.itefix.no/phpws/index.php?module=pagemaster&PAGE_user_op=view_page&PA
GE_id=12&MMN_position=22:22
http://www.itefix.no/phpws/index.php?module=faq&FAQ_op=view&FAQ_id=62

http://winscp.net/eng/index.php
http://www.webdrive.com/products/webdrive/index.html

Windows XP also has a built-in PPTP VPN server and client that may work for
you...Use a strong password...

http://www.onecomputerguy.com/networking/xp_vpn_server.htm
http://www.onecomputerguy.com/networking/xp_vpn.htm

Lastly, if you are on broadband ISP, ie. DSL or cable, you could look into
using VPN end-point type router at one end so the remote user can access the
LAN and/or PC via a VPN... Lots of manufactures build those. Examples are
Linksys, Netgear, D-Link, etc...