i have similar setup, but i do not connect to a service, but rather connect 3 other homes in my immediate family. so we have a secure network between our homes.
I purchased several cheap atom based fanless PCs with 1 gb of memory and a small hard drive off of ebay for the OS. i installed centos 5.x and set up openvpn on each of them. 1 of them, at my house, is the vpn server. the others run as VPN clients. The connections are kept alive 24/7. my server machine updates a dyndns domain name for any Dynamic IP changes at my side.
over the secure network, we run file sharing and voip. i routinely remote into their desktops via RDP or SSH into the centos boxes to perform maintenance (very little maintenance actually).
I use one of the remote boxes to mirror my file server using rsync. it's cheaper to hang a USB hard drive off the remote box than pay for an online backup service. and since this is my family, i'm not concerned about physical security of the external usb hard drive.
all in all i think this cost me approx $350 to set up 4 homes.
the most difficult part was adding the correct routes to the various remote routers (3 different vendor routers all have a different way of entering routes to their tables). ensuring the routes at the local and remote end are correct allows any machine on the network (remote or local) to get to the VPN and out on the other side and hit any machine there.
good luck. hope this helps.
edit: here is an atom pc that is much better than mine and cheaper: »www.ebay.com/itm/Wireless-Dell-O ··· -content