I'd head over to www.tivocommunity.com and ask there. You'll need to be a bit more specific on how you're set up. The description you provided wasn't entirely clear (and I'm pretty savvy with these things )

From what you described, I *think* you've got

1. An internal network with a router to the outside (via SBC).
2. A TiVo on the internal network
3. Another (or multiple) additional computers on the internal network
4. YOUR computer, work issued, with whatever software they have loaded
5. You can connect your computer at home and access your work files via a VPN
6. You can access the TiVoToGo web pages, but cannot seem to download shows from the TiVo.

Right so far? Ok, let's try a few more
7. Can you access shows from your wife's laptop which is on the internal network and doesn't have any VPN software running?

From the TiVo support area
http://customersupport.tivo.com/know...lic/tv2161.htm
it would seem that you need certain ports available in your laptop firewall. See bullet 7 in the link. Seems like ports 2190 (TCP/UDP) and 8080-8089 (TCP). Much of the other communication is probably over port 80 (i.e., schedule shows, etc) since part of the TiVoToGo implementation is vial http requests (like web pages).

One additional question
8. Do you start a VPN connection all the time you use your laptop? Or can you start with a local mode?
For example, my work laptop has a remote connection application I need to use before I can access my on-line email, internal web pages, etc. My browser has, by default, all the proxy settings too. But, they (only recently) have allowed non-VPN use ("hotel proxy off" is the name they use for this). From home, try it without logging into your corporate network. This may enable your laptop to see the tivo.