logmein.com, but you should really talk to your IT guy or gal. They might have a better option or have to open up a port on the FW. And you might be breaking some sort of trust agreement buy installing remote control software on a company pc.
I would have suggested remote control software from Proxy Networks. I use it to manage several projects remotely and it has never let me down yet. If Netman ever fails to live up to your needs, give Proxy a look (free demo!!).