Reset oid , starting value=1

Hello,
i have a bug in a php application based on postgres 7.2.2 , which cannot
handle oid's greater than
2147483647 .
So I have to reset the used oids to start from 1 again, so that we have more
time to correct this bug, I tried to delete dropdb, createdb and read back
the data, but the oids are not reseted , they start at the high values.
How can i reset this oid-starting from value ?
Are OIDs used once per postgres-installation (so they are unique over all
databases, seem to be that way) , or are they only counted up in the current
database ?
There must be a global value which sets the last oid, i need to set this to
"1" or to fill up from 1 , so i have no oids >= 2147483647 for the near
future.. how can i do this ? Fixing the mentioned above will take more time.

What i am looking for is a vacuumdb -a --forgetthoseoids ;-) , but I cannot
find infos about that.

bye,
Andre Gellert