Slightly edited

the name of the thread because have
some more questions on it.
So...
1. Installed by
getvirtualbox and there installed Windows XP sp1+2.
Edit: I realised that I installed Oracle VM Virtual Box Non-OSE so the following question about installing OSE additions is stupid. 
You have not to read further.
2.
- Now the mouse (serial) doesn't work in the Windows area. Clicking on it always gives me the warning about capturing the mouse with the buttons "Capture" and "Cancel" but the mouse doesn't work when I choose to capture. (
edit: there was a warning that Windows can't work with the mouse at the current screen resolution which was 1280x1024; changed to 1600x1200 but that didn't help)
- The Windows area is too small and won't expand with expanding the VB window.
I went to Synaptic and saw there I can install:
- dkms-virtualbox which is Kernel support for VirtualBox OSE;
- dkms-vboxadditions - Kernel module for VirtualBox OSE additions and
- virtualbox-guest-additions - allows to share files with the host system.
All of them want to uninstall
getvirtualbox; I think it's a metapackage and it can be uninstalled w/o damaging VB itself.
I hope this could help me for the mouse/screen issues but I am not sure.
3. So I'd like to kindly ask should I install them?