your netbook should have a hidden recovery partition on HD, used to restore windows.
If you don't touch/delete it while installing ubuntu, then you should be able to use it in case you want to go back to windows.
Besides, from your windows installation, you should be able to burn a DVD containing a full backup of your OS, just check the Samsung utilities, the option should be there.
You need an external DVD burner to do it (of course), but I highly suggest to do it if you care so much in preserving the original windows.
Please consider a little donation to keep the 'Linux On My Samsung' project up and running. Thank you!