wayne128 wrote:This brings me to my next question...
If I delete the 9.04 partition using Gparted, how will this affect GRUB? Will GRUB be automatically updated or will I have to manually edit this before or after deletion?
When you use gparted to manipulate partition, especially DELETE a partition, you have to prepare for unbootable OS partitions

( those with partition number higher than that one you deleted)
So if you want to delete sdb1, all the rest of sdbX partition will become unbootable
Your first paragraph is only partially correct, and the conclusion in the second paragraph's conclusion is uncertain.
Certainly deleting a partition on which GRUB resides will cause everything booted from GRUB to become unbootable. Since GRUB normally boots or redirects the boot process to everything on the computer, this means that deleting GRUB's host partition (normally Linux's root or /boot) renders everything unbootable. The numbers of the disk partitions are irrelevant to this question.
If you delete a logical partition (one numbered 5 or above), booting partitions with higher numbers
may be disrupted, depending on how they're referred to in GRUB or other boot loaders, since the later partitions' numbers will change. This shouldn't be a problem if you use UUID numbers to refer to partitions, as most GRUB 2 installations today do.
Deleting a primary partition should not affect the bootability of any other partition, unless of course the primary partition holds GRUB. Deleting a primary partition does not affect the numbering of any subsequent partition.
In the case of Gyrotwister's configuration, it's unclear where GRUB is installed and therefore how the bootability of the computer will be affected by any changes. These details can be provided by the
Boot Info Script. After running it, post the RESULTS.txt file here (preferably tagged as code or as an attachment) for interpretation. This might not be necessary, though. If you delete a Linux installation's partition(s) and then install another Linux distribution in its place, chances are the new Linux installation will install a new copy of GRUB. This new GRUB will almost certainly boot the new Linux, it will probably boot Windows or other non-Linux OSes, and it might boot other Linux distributions. Thus, after installing a new Linux, everything might boot normally from the start, and if it doesn't, you'll almost certainly be able to get into a Linux system to fix anything that doesn't work.
That said, any sort of partition manipulation, OS installation, or boot loader installation poses risks. There's always the chance that something will go badly wrong. Make backups of your work, and don't attempt such changes unless you can afford to spend several hours fixing problems, should they occur.