Newbie - how to VPN/remote desktop to Corporate

Hi,
Hope I'm in the right place, one year old Mac Newbie-

Have MacBook w/Leopard.
Have Parallels 4.0 and WinXP.
I use Cisco Anyconnect and then Remote desktop in to corporate Wintel notebook at work. Works great.

Now... how in the world does this Beancounter get into my Wintel notebook workstation at work from the Mac desktop at home?

I simply want the same functionality I have under the first case.

Is there software I need and on which computer (work=host, client=home I presume?).

I Googled and tried VNC and am getting lost in the documentation, IS guys have placed this as low priority - although one has an iPhone and is working on 'em.

I know my home/client IP address and I do have the work IP address, what's worked best for this group?

Thanks!
P.S. This my attempt to avoid getting a Vista box...(had one, too painful...) and then getting the Business/Ultimate edition because only those editions have RDC whereas XP works fine. That's why I like Leopard -
One flavor
Time machine
Don't really need to buy extra software
Things tend to work, the software/hardware integration, what a concept.