Partitioning a hard drive

[AZ]

I'm trying to reinstall LL on my hard drive after losing wifi after I installed the updates. When I go to install LL using the CD, I have the option to install LL alongside Windows XP. I already have LL installed alongside XP. I don't want two LL operating systems & XP installed. I want to reinstall LL over the existing LL. I believe, I have to delete one of the partitions (number 5) but it won't let me. Below are my partitions on my hard drive. Any help would be much appreciated. Thanks

AZ

linux@linux:~$ sudo parted -l
Model: ATA WDC WD600UE-22KV (scsi)
Disk /dev/sda: 60.0GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start  End    Size    Type      File system    Flags
1      32.3kB  47.3GB  47.3GB  primary  ntfs            boot
2      47.3GB  60.0GB  12.7GB  extended
5      47.3GB  58.5GB  11.3GB  logical  ext4
6      58.5GB  60.0GB  1473MB  logical  linux-swap(v1)


Warning: Unable to open /dev/sr0 read-write (Read-only file system).  /dev/sr0
has been opened read-only.
Error: Invalid partition table - recursive partition on /dev/sr0.       
Ignore/Cancel?