problem with chmod

[Thorny]

[...]
> I want to be able to access what is in those two partitions - read and
> write access, from the Debian partition.
> 

Once they are mounted, they become part of the filesystem of your Ubuntu
installation. They will have permissions (properties) according to the
location in the filesystem and/or the way you choose to mount them.

[...]
> I do not ant that partition to be used as the /home partition for
> Ubuntu.
> 

No, I suppose you don't, I hoped that question would make you think about
where you wanted them mounted. Remember, that you can read and write files
in your ~home, so if they were mounted there you would have read and write
access there.

[...]
> But I have previously been able to access /mnt/data partitions and
> underlying directory hierarchies, as a user, with Debian 3.1, with
> read/write access, and so I assumed that I would be able to similarly
> access these partitions from Ubuntu.
> 

Sure, it's possible for root (sys admin) to change those permissions, it's
just generally a better idea for an inexperienced user to leave standard
filesystem permissions as they are and mount things where they have the
access they desire. Not a hard and fast rule, it's your system to choose,
however, you need to understand how things work or you have problems. eh?