If you're one of the many iPad customers having issues with charging, there may be relief in sight. A few popular PC motherboard manufacturers have released new drivers for their mobos that supposedly enable (or help with) iPad charging. If you have an ASUS, Gigabyte, or MSI motherboard, you can try hitting those links, downloading and installing the new drivers, and see if that helps. Unfortunately, this is still a YMMV situation -- there are a ton of different factors that go into the kind of power that can come off of a USB port, and even if you have the right software for the right motherboard manufacturer, there's no guarantee it'll work exactly right.
Still, if you've been craving a little extra power while charging your iPad on a PC, and know your way around a motherboard software update (which can be quite a task in itself, let me tell you from experience), attempting an update might be worth it. If you get it working and see an improvement in your iPad's charging capability, be sure to let us know in the comments.