Since you have an LE, you have to enable HyperZ ,and up the clock speed from the default 148 MHz. There is a nice
tweaker that can do this for you, or if you like to do it the old fashioned way, these settings work well.
REGEDIT4
[HKEY_LOCAL_MACHINE\Software\ATI Technologies\Driver\0001\atidxhal]
"EnableWaitUntilIdxTriList2"="1"
"TableFogEnable"="1"
"WFogEnable"="0"
"ZFogEnable"="1"
"DisableHierarchicalZ"="1"
"DisableHyperZ"="0"
"FastZClearEnabled"="1"
"Vsync"="0"
"AntiAlias"="0"
"ZFormats"="15"
"ExportCompressedTex"="1"
"DitherAlpha"="1"
"ExportWBuffer"="0"