SQL SERVER 2005 slow Performance on Windows Server 2008

recently i upgrade my server to new one. but because of compatibility issue with my old Windows Server 2003 R2 32 bit, i also upgrade it to Windows Server 2008 R2 64 bit. (i have install Windows Server 2003 32 bit & SQL Server 2005 32 bit on the new Hardware and run without problem thou sometimes the windows freeze because of compatibility issue with the new hardware) after upgrade to Windows Server 2008 R2 64 bit, i still use the old SQL Server 2005 R2 32 bit. i can install SQL Server 2005 R2 32 bit on Windows Server 2008 R2 64 bit and make it run. the problem it run slower than on my old Windows 2003.

what i do on migrating? i deattach the LDF & MDF file and backup it. install new Windows and SQL Server. Attach back the LDF & MDF file.

is there anything i miss or there is also compatibility issue using 32 bit SQL Server running on 64 bit Windows Server? Thanks.