did you try to repartition the entire 80 gig drive?
If you did then no doubt when you wrote it to the mbr it converted it all to linux's system.
basically the two filesystem types that you might want to run are jfs2 or 3, as you can guess three is a newer version of of the journaling file system.
As far as it not being accessable from windows, thats not entirely true, you can install a program called samba that will allow a certain ammount of communication between the systems.
What you basically will have to do is to use windows fdisk to make say 70 gig of the drive windows, leaving about 10 gig just free unused by any master boot record.
Then when you put in the installer it should ask you about partitioning, at which point you can make that 10 gig be linux. That should be the easiest way to partition and not have any issues. Mbr's are finikey
Btw good choice on a starting distribution. Hope you enjoy your experience with linux and come back to ask any question if you have other issues.