Your XML sample did not make it. (you need to escape the < with < )
Concerning accessing attributes you can do this with the @ sign like:
OPENXML(@iDoc, '//a:category', 1)
WITH (
[category] nvarchar(50) '.',
[startdate] nvarchar(50) './@start',
[enddate] nvarchar(50) './@end'
) XmlSet
see http://www.sqlservercentral.com/Forums/Topic416002-145-1.aspx#bm416034 for one example.
Regards,
Andras
Andras Belokosztolszki, MCPD, PhD
GoldenGate Software