Reformating created extended partition/logical drive. How come?

[h20]

Hi,

So before I formated my hard drive i had 2 partitions.

A C and a D

I decided to reformat the C drive that has XP on it.

After the format I checked out disk management.

How come the C drive is now an extended partition and logical drive? The D partition remains unchanged

Does this influence the performance?

Please do not create two threads on the exact same topic. One thread is enough. Thank you.