SharePoint Web Service(4)- Crazy blank

This time, I will told you a story about crazy blank. When I was trying to create a new item with a Hyperlink field like my previous post like below:
string strBatch = @"<Method ID='1' Cmd='New'>
                                <Field Name='Title'>Sample Title</Field>
                                <Field Name='Url'>http://www.microsoft.com,Microsoft Site</Field>
                                </Method>";
Could you tell me what's wrong with this code snippet? I think most of you can not tell it. I spent hours trying to find the error. Finally,...
string strBatch = @"<Method ID='1' Cmd='New'>
                                <Field Name='Title'>Sample Title</Field>
                                <Field Name='Url'>http://www.microsoft.com, Microsoft Site</Field>
                                </Method>";
Could you tell the difference between these two code snippets? Yep, the blank, the blank after the comma. Hope it would help you.