Standard alternative
Try this one if the one above is not working. Some reports that Excel 2003 need the exta OLEDB; section in the beginning of the string.

OLEDB;Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\MyExcel.xls;
Extended Properties="Excel 8.0;HDR=Yes;IMEX=1";
"HDR=Yes;" indicates that the first row contains columnnames, not data. "HDR=No;" indicates the opposite.

"IMEX=1;" tells the driver to always read "intermixed" (numbers, dates, strings etc) data columns as text. Note that this option might affect excel sheet write access negative.

SQL syntax "SELECT [Column Name One], [Column Name Two] FROM [Sheet One$]". I.e. excel worksheet name followed by a "$" and wrapped in "[" "]" brackets.

"SELECT * FROM [Sheet1$a5:d]", start picking the data as of row 5 and up to column D.

Check out the [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Jet\4.0\Engines\Excel] located registry REG_DWORD "TypeGuessRows". That's the key to not letting Excel use only the first 8 rows to guess the columns data type. Set this value to 0 to scan all rows. This might hurt performance. Please also note that adding the IMEX=1 option might cause the IMEX feature to set in after just 8 rows. Use IMEX=0 instead to be sure to force the registry TypeGuessRows=0 (scan all rows) to work.