I seem to get a cache memory build up with SQL Server, Delphi 5 on a Windows
2000 server. I  reboot the server every now and then, it seems to help. How
can I issue a command from Delphi that will flush all cache buffers.

My SQL server log file also grows larger all the time. Is there a way to
control this from within Delphi if I dont want to use "Transaction.Commit".
I was told to use DBISAVECHANGES(..) but that doesnt seem to free up RAM.
The server has 128 MB RAM and the database gets about one new record every 5
seconds at a constant rate.

you can try to shrink the transaction log by setting truncate on checkpoint
to true and calling checkpoint in SQL. Or, you can back it up.

MSSQL 7 memory config, by default, will use all the memory it thinks it
needs, but will release it if it can upon pressure from other apps on the
machine allocating memory.