Windows XP SP 2 settings for 802.1x implementation

Hi all,
please help with proper Windows XP SP2 registry settings in wired 802.1x implementation.
There are two problem.
First, after successfull user authentication VLAN on a switch port was changed, but IP address still leave old (IP address is changed only after re-authentication, if this parameter is set, or after cable was unplugged)
We don't want play with cables plug/unplug, so PC should get new IP address when VLAN was changed.
Second, user authentication process (as a supplicant) is working in parallel with WinLogon procedure and getting policies. WinLogon doesn't wait, when 802.1x authentication will finished, and requests to DC, when switch port is in a guest VLAN with no rights to access DC. How prevent WinLogon to wait.
It should be settings in Registry. I couldn't find proper recomendations.
Please help.
Valentina