It's likely that your school's the problem...lots either don't allow p2p use or shape bandwidth for p2p.
Bandwidth Shaper Sample - typical of how some schools use it (click on link)

Do any other people at school use LW & see good speeds? Actually, you're lucky that the school's not blocking it completely.
Double check that your XP firewall is allowing gnutella, although the school's probably got it's own firewall too.
You could talk to the school's admin & find out what their policy on p2p is :wink: