It's quite unusual for a device to get into a rebooting loop like that. I'm afraid the only thing you can do is restore it using iTunes
if another reset does not stop it looping.
In order to do this, you may need to put the device into DFU mode. This is quite simple and I have written a guide on it in the link below. DFU mode will prevent it constantly rebooting and allow iTunes to recognise the iPad and restore it.
http://www.ipadforums.net/ipad-hacking/27489-dfu-mode-dummies.html
iTunes will prompt you that it has found a device in recovery mode and you should restore it. The only option available will be to press the "restore" button. This will download a fresh firmware from Apple and restore your iPad to factory new state. Once this process completes you will get the choice to set up the iPad as "new" or restore from a previous backup. If you recently synced with iTunes and want to have your iPad set back up with your data and apps / music / etc., you should choose the second option. Otherwiese, if you choose "new" you will have to manually put all your apps etc back on the iPad manually and provide settings for all your apps again.
Hope that helps.