MSSQL-NT

I m configuring MS SQL Server 6.5 with service pack 3 memmory to 512 ON Win NT 4 having Service Pack 4 with (1GB + 128MB) RAM. I want know how much memory maximum I can allocate to MS SQL Server 6.5 with service pack 3 and Winnt 4 having service packe 4.Do Have I to install further service packs on NT or SQL. Please Help Me Out