|On many brand name computers, the Recovery partition on the original single hard drive contains all the data that is needed to re-load the much larger first partition you see as C in Windows with it's original brand name software installation. |
If you alter that Recovery partition in any way, it is likely that you will not be able to reload that original software on what you see as C from that partition, because the Recovery program will refuse to load.
You can't make the partitions larger or smaller with what's built into Windows XP and previous Windows versions without deleting all the data on the partition first in any case. You would have to use a third party program to do that if you don't want to lose the data on C .