.dll files

[peterpanoah]

this is .dll files of my cabal folder:
1.d3dx9_30.dll
2.atl71.dll
3.fmodex.dll
4,fmodexL.dll
5.libogg.dll
6.liboggbis.dll
7.liboggbislife.dll
8.xpva00.dll
9.xpva03.dll

where is important .dll files and cannot be change .dll file like .crckd.dll
i hope someone answers my question,sorry my english is bad,because i from indonesian,thx