I dual boot my machine between XP and CentOS with GRUB in MBR.
I did something wrong with grub.conf, and ever since I can't boot XP. So, re-instated XP MBR using XP boot disk.

Now I am trying to get CentOS back. I booted the machine with CentOS disk, and selected F5 (rescue), but it doesn't go into same rescue mode like other linux installations. It goes into a phase where I have to select partitions to format etc which is uncalled for. Reclaiming MBR is not such a great step and I have done it with FC and Ubuntu before. But in CentOS Is there a simpler step I might have missed when getting into Linux rescue mode?

If you boot up the Live or installer CD it should show some choices at the bottom of the screen, one of them being "linux rescue" or like that.