c3310.z1301.winmx.com is the hostname (friendly address) of one of the original winmx peer cache servers.
Before they shut down what happened was winmx used the same system to look this up to find it's IP address that your internet explorer does (DNS)
The hosts file fix works because windows has a file it looks in for this information BEFORE it looks online to find the IP.. called HOSTS, it's really just a list, as servers come & go this list needs updating.. There are consequently a number of versions of this around, with caches added (more ip's) etc.
The Winsock patch ws2_32.dll works differently, instead of a fixed list each user has to keep up to date it translates something like c3310.z1301.winmx.com to cache0.winmxworld.com this then gets looked up using DNS, which can be always kept current, without you doing anything manually, so if you're using the .dll you can be sure you're not trying to use any cache that closed or moved IP.. or that if there's a new one, your system knows about it (because DNS does).