How much faster does rapidshare run? Have you tried connecting to giganews on port 80 (i assume no ssl)? Both rapidshare and giganews have very nice bw coming into their servers. However, with giganews you have many simultanious connections (I assume the same does not hold true on rapidshare, I have never payed for premium). These extra connections should allow giganews to easily match or beat whatever speed you can get from the BEST single connection in the world.
In my experience, you should NEVER drop to 40KB/s ever... These companies (like rapidshare) have made MASSIVE investments in connectivity. There are people who easily max out 100m connections. Even on a modest connection such as yours, Your isp or home network is almost certainly at fault.
Is your cpu usage abnormally high when you have the insufficient speed? Try fewer (yes fewer) threads. With a good service you really don't need them. I max out my 20m line with 4-5, even during high traffic times.
The downside of many threads is higher cpu usage, and a more apparent hard drive bottleneck. If you are able to try the pay version, it caches parts (sections from each thread) in memory until they are combined. IMHO, this is an almost essential function when downloading from usenet.
Also, I have Kaspersky Internet Security. When I first installed it, I found that my processor usage was through the roof, and I got very bad speed. I narrowed this down by disabling kis and the speed went up, and cpu usage down. I was able to fix this easily by telling KIS not to scan any traffic generated by altbinz (adding it as trusted). Similar issues may exist on other av/firewall applications, try disabling them (at least temporarilly) and see if speed improves.
