That may have been the case a year ago, but now I'd say go ahead and get the free version.
The hackers and script kiddies like broadband because the IP numbers rarely change, making it easy to get back in touch with their compromised hosts. They love the bandwidth, allowing them to do more damage to the targets of their real attack. The hackers want to use your computer as a foot soldier in a attack on a bigger target.
Some Zombies are programmed to 'phone home' to a newsgroup for new instructions. This would defeat any security gained by having new IP numbers on dialup.
Anyone using VPN (Virtual Private Networking) or tunneling over broadband to connect with the home office, without some kind of firewall, exposes their office network to the same dangers.