Got your email, and your setup looks pretty good (ultrapeer works well).
There are a couple of things you can still do.

-check that your upload bandwidth is less than 90KB/s (this limits uploads overloading your setup).

-turn on Partial File Sharing (this should help when downloading from many sources)

-run a safe boot (restart the machine holding down the shift key), run Disk Utility's "repair permissions", and restart normally. Ask/or search the forums for more info/links on this step.

Run LW and test the magnet download again.

If no change, then

-update to the latest beta version (4.1.5) from the link on the bottom of your Pro page (assuming it is still active). If it isn't, just use the regular free version, or the latest open source build from http://www.mager.org/LimeWire/LimeWire.html
Better yet, help out the devs and renew the Pro.

You show Java version 1.4.1_01 from Apple Computer, Inc, which I guess is the latest for Jag (1.4.2_05 needs OS 10.3.3). Is Panther an option for you?