Update SQL Server 2005 SP2 to SP4 and cumulatives updates

Hi Gurus, In the EWA says to update my SQL Server 2005 SP2 to SP4 and update the cumulatives updates too (in this case cumulative update 3, the last CU for the SP4). Looking for the SQL Server 2005 SP's in the database patchs in SAP Services, i found the SP3 only, not the SP4. But in the sapnote 62988 says to get the lastest SP's in the microsoft site. My doubt is as follows, i update the SQL Server 2005 to SP3 or SP4? Do you have any tips? In case of update to SP4, i need to update the CU 1, 2 and 3 or only the cumulative update 3? Thanks in advanced. Cleiton Folster Eli.