First you could check in Open Office to see if there is the 'Arial' font. If so then you probably have the MS core fonts pack already. If not then you need to go past the installation sources to the actual list of packages available. At the top of the scree just to the left you can change whether you want installed packages, installation summary and others. I'm not sure where the font pack will be shown but I think it is in the available updates section. This will be shown at the bottom left of the screen. You'll probably need to scroll down as there are security updates in red to start with. Then if I remember rightly you get recommended updates in blue then optional ones in black. The MS core fonts pack is in black.
I couldn't find Arial in the OOo. So I don't think I have MS core fonts pack installed. I now are on the "Installation Summary". From here what do I do ?. Please have a look at: https://www.urbakken.dk/inst_summary.png Erik Jakobsen