To complete my post:
3 partitions have been successfully transferred by means of the Intel® Data Migration Software
1) Restore Partition
2) Windows XP System Part.
3) Data Partition
Then, I have used GPARTED (on live Ubuntu CD) to delete the Data Partition and move the blank space to the 2nd System partition. I have kept the 1st partition because it is less than 10GB.
Do you have other link to check or correct the SSD alignment on XP ?
--> To check the alignment: AS SSD Benchmark gives the info on the top left corner:
The Gparted solution given in the previous post (lifehacker link) seems to be good but it is always interesting to have other opinion, especially on this very technical subject.