VPN questions

Esteemed listers,

I am going to be taking home the iSeries Access and Cisco VPN Client install
CD-ROMs so that I can connect to our iSeries from home.

I am told that, once I activate a VPN connection, I lose my ability to surf
the internet at large from my ISP.  (I am told that I will only be able to
access the iSeries; the rest of the network will be unavailable via remote
access.)

Is this the nature of VPN?

FWIW, my connection is via cable modem, and I am using a GigaFast router.

>From the manual: This router supports only PPtP Packet Pass-Through.
Neither L2tP (Layer 2 Tunnel Protocol) nor IPSEC (Internet Protocol
Security) are supported.  The router itself does not have a VPN function.
It allows PPtP Packet Pass-Through.

tia,
db