I am on a Fujitsu Amilo Pi1505, Vista Home Premium and am having the same hassles. Every time you eject a USB flash it drops the Wireless LAN.
I have set IP to static,
Updated the Wireless LAN drivers,
Still no fix ...
Microsoft has suggested disabling IPv6, but I have not tried that yet.
I will also setup a link to the script you suggest to disable and re-enable the WLAN as an interim solution - a heck better than having to reboot each time.
Any other progress made?
I'll keep in touch.