I got it work so far, but when i try to install win XP, im getting a windows installation fatal error (error code 800b0101) "systemdateizeit ungltig", which means something like "invalid system time". As mentioned in vitualbox manual I entered the line "nohz=off" into grub boot loader options to make linux system time "tickles" (were there any ticks before?). I still get the same error.
Anybody any hints on that one?