This is one of the many things that was left out of the tutorial.
I had a problem with browsing to my share from windows after I created it. I could see it, but when I clicked on it, a username and password box would pop up. No matter what I typed, it would not let me in.
Finally, I realized that SWAT by default is set to USER level authentication. I changed this to SHARE, and I was able to browse my share immediately.
If this is your problem, then you just need to open SWAT (http://youripaddress:901),
click on the GLOBALS button, and switch the authentication from USER to SHARE.
If this isn't your problem, please provide more information.
Are you using Windows XP?
Is your windows computer in the same workgroup as your XBOX (right click on 'my computer', click 'properties', select the 'computer name' tab, click on the 'change' button).