So my system is set up like this:

/dev/sda1/ Windows XP Partition
/dev/sda2/ FAT32 Compaq Recovery Partition
/dev/sda3/ Container for Logical Partitions sda5 and sda6
/dev/sda4/ (can't find this one in Disk Utility)
/dev/sda5/ Linux file system running Lubuntu 12.04
/dev/sda6/ Linux swap space

Is there a way to just delete sda5 and sda6, boot with a Ubuntu 12.04 USB key and do a completely clean install of it to sda3? I'd like to check before I start deleting things.