Double-click the iCloud icon in your Task Tray. That should display the iCloud control panel. Make sure the "Photo Stream" option is checked, and that you are signed into iCloud (if there is a "Sign out" button at bottom left, then you are signed in successfully).
On your iPad, go to Settings, iCloud. Make sure you are using the same account as you used on your PC. Make sure that "Photo Stream" is "ON".
If all that looks good... Take a photo on your iPad. Assuming it is on wifi, the photo should sync to the PhotoStream folder of your PC within a few minutes. (The iPad must be on wifi to upload photostream.)
Existing items already in your photo stream may not automatically sync down to the PC. But new photos should. To sync an existing item, you can view it on your iPad, click the "box with arrow" icon and choose "save to camera roll". This will add another copy to your camera roll, and that should trigger the sync to iCloud (and then from iCloud to your PC).
If none of this works... I would recommend resetting your photo stream. Open IE on your PC, go to icloud.com, sign in. Click on your account name at the top right, click Advanced, then click "Reset Photo Stream". When that is complete, try taking another photo on your iPad. It should show up in the PhotoStream of your iPad immediately, and then (assuming iPad is on wifi) it should show up in your PC's PhotoStream folder within a few minutes.