slow network in XP

i just downloaded the SP2 upgrade for Windows XP Pro, and now it takes tthree times as long to load files from off the network.  i don't want to upgrade teh other computers if it will just make my network fail.

has anyone eles had this problem, and is there any way i can fix it?

Man, I get shitty speeds when tranferring files between two instances of XP compared to when I use FTP (something like 5x slower or more). What does that have to do with Samba?

My pet theory is the limitation is there to prevent a remote user throttling the response time for a local user on the host box.