Hello Giddaymate,

You're not the first one to be bitten by that &#$#%$& policy of allocating 3 (!) primary partitions for one OS.

Here is the fish you needed:
To get around the 4 primary partition limit, you need to create an extended partition. You can then create several (up to 16, I think) logical partitions. For example, you can have 3 primary partitions and one extended that supports several logical partitions. All the logical partitions must occupy a continuous block of disk space. The extended partition is named like other partitions sda1, sda2.... but isn't really a storage partition except to store other logical partitions. Linux does not care if it is on a logical or primary partition.

Now, here is a fishing rod:
The people who will help you on that kind of questions are member of the community more than Dell employees. So you would probably have quicker answers by asking those questions where the community is for now, namely http://ubuntuforums.org/

And here is even a fishing net:
If you google for:
ubuntu on dell primary partition site:ubuntuforums.org
the first result you will get is:
http://ubuntuforums.org/showthread.php?t=299802&page=4
On that page, this comment looks exactly like your question:
http://ubuntuforums.org/showpost.php?s=73183d696f809bc8e15e409ce9d673a9&p=2079310&postcount=36
and the following one... is the answer I cut and pasted above.

Happy fishing. :)
--
Sam Lee

When partitioning your IDE hard disk, note the following:

A hard disk can contain a maximum of 4 primary partitions.

A hard disk can contain only 1 extended partition.

An extended partition is treated as a primary partition.

An extended partition must be filled with logical partitions.

An extended partition can contain many logical partitions.