New clock resetting problem

[vistadude]

I have a macbook snow leopard and XP via bootcamp. When I first got the macbook, every time I restarted to move between mac os and windows xp, the clock would change by 4-7 hours. I used the trick of setting the windows time zone to the correct time zone, and the mac time zone to London GMT, and set the mac clock not to update by an internet connection. Everything worked fine for the past 3 months, until this week, when the U.S. enters daylights savings time.

Now my clock goes 1 hour behind in windows, and I think either the correct time or 1 hour ahead in mac. Does anyone know the "trick" to get the time right in windows and mac?

Thanks.