Note the quotation marks around handle. The only reason why Vista/7 are the most used OS's now is because it's something new, and something sleeker graphic-wise, which wows people. (Not to mention that most machines are usually updated with the latest and greatest OS so that the developers doesn't have to support previous OS releases).

Like I said before, if you have XP SP1 you have D3DX9_38.dll already in your System32 folder, there is no need for adding this into the folder.