If the magnetmix files download really slowly it's not a good sign. It can often point to an ISP throttling bandwidth for customers using p2p. That's why we ask people the name of their ISP...not because we're nosy.

You could try deleting LW's preferences folder while LW's closed. See points 2 & 3 in the thread below:
Fixes for LimeWire

You might want to update your Java as well, the latest version is update 9. See point 1 in the thread above. Just remember to use the offline installer for JRE.

How do you have your router set up (UPnP enabled, port forwarded or neither)? If you're seeing the firewall icon, you could enable UPnP within your router, if it supports UPnP. Then choose the relevant option within LW's tools > options > advanced > firewall config. Another option is to manually forward a port...the router's manual should have details.

Have you called your ISP to ask about throttling bandwidth (bear in mind that people at the helpdesk often don't even know that this kind of thing's happening)? Some research using Google might also turn up some info.