How do I check out a file in Sharepoint 2007 using either a remote service or HTTP call?

I can copy a file up to the Sharepoint archive using:

_vti_b开发者_StackOverflow中文版in/Copy.asmx.CopyIntoItems

but if the file already exists it insists that I check it out. Yet I cannot find a way of doing this?

Any help would be greatly appreciated!

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CheckOutFile

http://msdn.microsoft.com/en-us/library/lists.lists.checkoutfile%28office.12%29.aspx

CheckInFile

http://msdn.microsoft.com/en-us/library/lists.lists.checkinfile%28office.12%29.aspx