Leave your Trend Micro firewall on, but make sure that it's configured to allow LW. Make sure that any other software firewalls are off.

Try the tips here: Reduce the drag caused by LW
To disable ultrapeer capabilities in new versions, tools > options > advanced > performance. You can also try disabling Mojito DHT capabilities & see whether that has any effect.

The Java version that you'll link to from that post is now Java 6 update 3. Some people have had problems with the latest Java versions, so it's up to you if you want to try that one or not. I'm using it & it's fine for me.

This older version of Java has worked better for some of people. Download
the JRE offline installer & remove your current Java before you install this one.
Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11

Your modem's firewall might be an issue...do you see the firewall icon (brick wall in front of the blue globe)? If so, go to the site below
PortForward.com - Free Help Setting up Your Router or Firewall
and see if your modem's on the list. If so, you'll find instructions for port forwarding. If setting up a static IP is part of the instructions, don't miss this step. LW's listening port, port in the 'manual port forward' box & port forwarded within the modem's config should all be the same number.

For those crappy hosts, try adding this hostiles list: The TechNutopia Fullsize Hostiles List for BearShare and LimeWire