Would it not work to delete the new partition and resize the old one to use all the space -- that should ensure it is the correct size?
What new partition? 
In order to release some space on sda3 (the 19GB partition) I resized it (with PCC -> Manage Disk Partitions) to 10GB, leaving a space of 9GB behind it. That seemed to work. I then created a partition in the space just made and PCC said that the partitions had been renamed
It seemed to me that the partition got resized but the filesystem did not, so making the partition the size it was previously should bring things back to the way they were.
Maybe I missed something else ......
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Other way around. The filesystem got shrunk but the new partition never got made. Somewhere within the old partition is a filesystem of somewhat indeterminate size, smaller than the actual partition, by approximately half.
I've checked in XP and windows sees sda3 as 9.75GB, so it looks as though this partition has been shrunk
Seems I was believing that XP was seeing the partition and not the filesystem.
I have no recent experience with XP so do not know what it actually reports.
I guess backing up the data is the only reasonable course of action after which things can be sorted one way or another. The data should be accessible as it is the filesystem that is reduced.
regards.
