You CAN have file names with spaces (although, I prefer not to). And, you can easily run commands on those file names by enclosing the filename in double quotes... like this...
EXEC master..xp_cmdshell 'RENAME "C:\Webservices\datasource\TradeDetail04-02-08 00_00_00 .txt" TradeDetail.txt'
--Jeff Moden
Change is inevitable... Change for the better is not.