O.k. all problems solved! The ntfs-partition was not mounted because in the 2.6.7 kernel Sata drives are not longer labeled hd-whatever, they are now sd-whatever. So changing /dev/hde5 to /dev/sda5 in /etc/fstab makes it working again. The windows-ntfs-partition is now mounted at boottime like expected.
The problem with the Alcatel Speedtouch USB modem was a little bit more tricky. In the config-file which comes with the kernel is the speedtch module enabled. This will not work when you want to use the userland driver. In fact, I have never managed to get the module running with a pppoa connection which is used by my provider. So, I disabled the module in the config file, recompiled the kernel, rebooted, used my standart way to connect to the internet and the sun is shining again....