Pivot
OK now I sorted out my problem with pivoting tables.
Thanks Access, no thanks to SQL Server :-((
It's a pity that you can do a so nice SQL Transform and Pivot function with Access and not be able to do it natively in T-SQL !
Other problem, and I reckon it was my first time on the matter, if you have to deal with stats, and I mean huge stats, it would be nicer to have a bigger number of columns, whatever the tool, Access, SQL or Excel.
By the way, if somebody know a spreadsheet application able to accept 3000 columns and 10000 rows, please let me know.