How secure is VPN access?

[Cesar Diaz <cdiaz00 () gmail com>]

List,

After years of having VPN access for our remote users without a single
know security incident, my boss and I have to justify to her boss why
VPN is secure.

The CIO wants us to only allow users to access the network from
company laptops, not from their own home computers.  We currently will
allow users to install the VPN client software on their home computers
to connect remotely, or they can use Citrix through SSL access to get
to network resources.  His concern is that if a users home PC is
compromised, that compromise can spread to our network.

Is this a legitimate concern?  Can anyone point me in the direction of
some documentation backing either argument?

Thanks in advance for any help.

C