First of all, don't panic. If you blocked that URL and don't visit it again, nothing will happen. Now, step back and read the documentation of the software you bought — at least I would carefully read it if I was worried about my security.
From the manual:
VirusBarrier X6's Antivandal watches over data entering your Mac and filters it, looking for signs of intrusion. This filtering is transparent: the only time you'll see signs of it working is if it detects suspicious data, in which case an alert displays. Otherwise, Antivandal silently monitors your Mac's network activity at all times.
With regards to port scans, VirusBarrier mentions this:
Attempts by remote computers to search your Mac's ports for vulnerabilities. You may want to leave this unchecked if your computer is functioning as a server.
This simply means that the website you visited made a server check your computer's (or rather, your router's) IP address for open ports. This, per se, is not harmful. There are even dozens of web sites dedicated to doing just that (like this one).
If you sit behind a router, or your Mac has a firewall enabled, that's nothing to worry about. If you run a production server on your machine, I'd be more worried, but even then this is no active intrusion or an attempt to get a virus onto your machine.
Is it possible that a virus on my Mac could capture my details (netbanking password, etc)?
A virus could do pretty much anything on your system, but given the situation you explained, there will most probably be no virus on your system.
What should I do? Do I have to reinstall OS X and install all software again?
No. Continue using your machine as before and maybe be a bit more concious when browsing. Don't download anything suspicious, and don't install software you don't trust.
Leave VirusBarrier running if you want. But you can trust me that hundreds of thousands of Mac users do not run such software and are still reasonably safe if they know what they're doing.
If antivirus software has captured it, do I have to worry?
There was no virus to be captured. You have nothing to worry about.