Hey Blake,

Lots of people have had troubles with Vista & McAfee. Have a read thru these threads & use the forum search to look for McAfee (or just have a look thru this Vista section)...you might find some more info

Can't Connect With VISTA!
“No Compromise” Vista-McAfee-Limewire Solution

Grandpa uses Vista (I don't) & he also recommends Avast!
Avast

Once you've got McAfee sorted out, you might need to port forward for your router (it has a firewall of it's own, so port forwarding should get rid of your firewall icon). The instructions are here.
Port Forwarding for the Linksys WRT300N
Don't forget the step of setting up a static IP address! LW's listening port, port in the 'manual port forward' box & port forwarded thru a router all have to be the same number

If you're still having trouble after all that, reinstall your Java. Just remove your current Java version & reinstall using the JRE offline installer.
Java SE Downloads

And delete LW"s preferences folder when LW's properly closed. See point 3 here (also point 2 if you've used much older versions of LW on the same computer before you changed to Vista).
Fixes for LimeWire
Sticky: LimeWire Pref Folder in Vista