There's a reason why iBurst says you need updated firewalls and antivirus software on their main site :
PEOPLE ARE IDIOTS. Especially idiots... yes.... I classify them as a whole race. If you see an idiot, run... they can be really sly, so if you find an idiot, run. They won't be offended.
To your question, yes, the IP range is there for people to block potential dos attacks or port scanning or virusses or whatever trying to get into your PC (or kill it) while using P2P software. P2P software basically broadcasts your IP to everyone sharing the same file as you, and if someone maulicious enough wants to make your life a living hell, they can.
However, firewall helps you there, including latest virus definitions, so it shouldn't happen, but for added security, you can download the filter.dat and read it into your P2P program that can then block all of those IP addresses that will try and cause you harm.
There has been a huge influx of attacks on my PC in the last week or so, from iBurst IP addresses. Same thing happened to Sentech when they started out. Sentech only made deals with firewall providers and mcafee to distribute the software to their clients as a precautionary measure because people (those idiots) have no clue.
Telkom has done it with ADSL, I can't understand why this hasn't become a standard practice for 24/7 connectivity.
iBurst hasn't come to the realisation (like Sentech) that they're an INTERNET SERVICE PROVIDER and not just another dude selling modems. They need to take measures to protect them and their clients interests. Which they obviously don't