[Live-demo] osgeo took my computer

[maxion at zedat.fu-berlin.de]

Hello people,
i have tried to install osgeo live on my HP-Computer which has already
Ubunut 11.10 and Windows 7 on it. i started with downloading the big
package (with windows installers)osgeo-live-5.0.iso with ubuntu 11.10 and
burned it on a dvd, in the end i did NOT verify my download with this file
(osgeo-live-5.0.iso.md5)and i still don't know how this should happen.
Anyway the dvd seemed burned succesfully.
Then I entered the dvd and got right onto the PXE terminal and chose
install directly on hard disk.
I chose a partition of 100GB for Osgeo 5.0. The installation started but
failed after a while.
So I turned off the computer aftewr i took out the dvd, then i started
again and did not get onto the PXE but on the usual window where i can
choose between Ubuntu 11.1 and Windows 7 to boot.
I started Windows and tried to delete the 100GB partition but I was not
able to do so, it said there was not enough space in the directory to
delete the partition.
Then I put the dvd back into the computer and rebooted, I got to PXE and
chose to start Osgeo live from the dvd.
It worked and in Osgeo 5.0 i was able to access all data from Windows 7
partition and the 100GB partition which i have created during the failed
installation. Additionally I saw a third file system which was probably
the dvd itself.
When I shut down xubuntu/osgeo and start the computer without the dvd I do
NOT get to choose whether i want to start Windows 7 or Ubuntu 11.1 but
instead I am asked to enter the system disk and then press any key. I
changed the booting list, so it does not boot from dvd first, but the
problem returned.
How can I boot Windows and Ubuntu again, how can delet the wrong 100GB
partition and how can I install osgeo live onto my hard disk but still be
able to boot windows or ubuntu?

Thanks for your help

Greets
Max