Remote Control Pro was freeware (a showcase program for its company) but we recently heard it was developed much further and is now Shareware.  This is not a bad thing really for such an excellent program.  If you can still find the free version then use it, but if not - buy the new one.  If you really want to see the difference, try out one of the VNC family and then try a trial version of Remote Control Pro.
http://www.alchemy-lab.com/products/rcp/

A note about Firewalls...

If you operate any remote software and find you cannot connect, the reason is nearly always a Firewall block.  It is a paradox - you want to protect yourself from anything coming in or out, then you decide you want remote access.  Its like wanting to have your cake and eat it.  A proper Firewall setup should ask you at both ends if you want to allow this software to communicate.  At this point you should say yes, and tell it to remember your choice.  Unfortunately some Firewalls go a bit wonky and sometimes don't ask, or don't remember.  If this starts occurring with any software you should reinstall the Firewall to get it to function properly again (or better still upgrade to a better Firewall).

Some Firewalls give you better access to its operation, so you can manually add your software to its list and even limit what it can connect to.  It can also let you delete anything erroneously blocked.  Again, if your Firewall doesn't give you this facility, get a better Firewall that does.

If you have a router connecting you to the internet, the router may have its own internal Firewall (most do).  In this case you will need to consult its manual on how to allow restricted access for your software.  Routers do not 'ask' permission, they just block silently.

So, if you cannot connect, first check out your personal Firewall.  If you still cannot connect, try turning OFF your Firewall to help discover if it still is the culprit (make sure you disconnect from the internet first - never ever turn off a Firewall while connected - you are likely to be attacked within minutes).  If you still cannot connect, check the router and find out how to give it permissions needed.  Don't forget to re-enable your own firewall before connecting though.  And remember that all this needs to be checked at both ends, the remote pc aswell as this one.

While Firewalls can seem a total pain at times, they are vital.  No-one should even dream of connecting to the internet at-all without a Firewall installed and running.  Its nearest analogy would be going on holiday and leaving all your doors and windows open in an empty house.

If you have never looked very deeply at security for your pc, check out our security reviews sections for valuable extras that will give you a lot more peace of mind.