Partions

The partition editior should be able to adjust the sizes of the partitions on your drive (shink one and make another larger), but you can't modify the partition that Nexradix is running from while it is running.  That's why you're getting that "lock" icon -- any mounted partitions can't be modified.

To resize, just boot your system with the Nexradix installation DVD, and enter the live mode (select the first option: "try Nexradix without changing your computer").  Then use the partition editior in the live environment, and you should be able to adjust the sizes.   A warning: the resize can take a very long time, depending on various factors.  There is also always the chance of data loss during such operations, so be sure to back up all important data beforehand.