I'm most used to the traditional Debian text-mode installer where you manually partition your disk. Even granting new GUI installers are more intelligent, the question is how intelligent?
His old disk is using some MBR scheme, which is limited to 4 primary partitions. Does the existing install use extended partitions? Ubuntu 10.x is very old, so I don't know if the default was LVM or not.
There are enough variables here that the end user has three general options:
- Nuke everything and install from scratch (he loses Windows XP, no loss). The installer will choose reasonable defaults.
- Understand the current partitioning scheme and adjust it accordingly. The simplest case would be a single primary partition for Linux, and using a swap file. No need for multiple filesystems like the bad old days.
- iAsk a Linux sysadmin