Report in Sharepoint

hello!
about report in Sharepoint:
in Moss it is possible to view statistic data access for site in last 30 days. it is possible to modify this period?
for example, modified a file xml..?

In sharepoint designer 2007 it is possible
to view the basic report(usage, last s.o…)
how SPD 2007 read the data for create a report?
thank’s