Remotely access computer

I am using winxp sp2 and would like to be able to access my home computer when I am away.
I have adsl connection but no fixed IP address.
So the win xp builtin remote access is not good for me.
I recently saw on the web that there is a mywebexpc site that offers the possibility to access my home computer remotely for free, but I am not to connect to it before knowing what is the catch for that “free” site; my upbringing get me hooked to the idea that there is no free lunch, so what is the price we really pay for that kind of “free site”?
Anyone can offer an explanation?
Thanks for your input.