Slow Airport Express

Can anyone shed light on this one?
I have an iMac G5, 5512 meg RAM, OSX Tiger.
I have a home wireless network connecting my iMac to another G5 and an XP box. Until last night, everything hummed. Last night I updated the firmware on my Airport Express and replaced the default 'public' password on the AP.
Now - the connection between G5 and XP box is SHOCKINGLY slow. A file transfer that took 7 minutes yesterday now takes 52 minutes.
HELP - any ideas?

Thank you.

My wild guess would be the firmware update boinked you. Try re flashing back to the old firmware see what happens.

Also check to make sure that you are getting good signal strenth on both machines as a low signal will significantly reduce the speed at which you can transfer files. (Obvious?)