The problem with any form of publishing that desktop machine onto the internet, be that by port forwarding or by giving it it's own address, will be security. Suddenly you've made a hole into your corporate network that publicly readable traffic will flow through.
VPN'ing is safer in that it's at least encrypted and the "hole" in the network is password protected.
Both though allow things from outside your network to reach inside, and that is a security risk, and I wonder if that's why the IT person is being so unhelpful about this. It's just a world of awkwardness, even more so if the company network faces audits for any reason (e.g. holding credit card data).
And that's why something like GoToMyPc could be a winner, nothing reaches into the company network, all network links are established outwards from both machines.
But that said I've never used it. I thought it would be like remote desktopping, which I have done for extended periods of time and I think is fine, but niceguy2 seems to suggest that it could actually be different and quite painful...
GoToMyPc does at least allow a free trial so use can begin immediately, and during that free trial the IT guy might finally sort out a "proper" way of allowing the required form of remote access.