iPad 2 does not charge from most windows and old Mac Laptop

iPad 2 has a very weird behavior that it doesn't get charged when connected to most of the laptops.
It requires a new Mac machine to get properly charged. Or else you need to have the wall adapter shipped with iPad2. Even an iPhone wall charger is slower in charging iPad2.

The issue here is iPad2 requires more power to charge, which new Mac laptops and Mac OS is optimized for.
You can have the trick on Windows based PCs with some USB drivers and to date something that works is an ASUS driver that works on Asus motherboard based laptops and also some other laptops, mostly dell laptops may be because dell uses Asus internally for its motherboard. But some people has reported issues with their machine after installing this driver. Its a mess uninstalling this driver which might mess us usb drives and some registry tweaks is required to fix it.

Actually PC can recharge iPad, but iPad has to be in the sleep mode, but then too the charging is slow.
The normal USB are 500mA, which the iPad2 wall charger is 2Amp.

Some good experiences are shared on this apple discussion forum.

The ASUS driver link is: http://event.asus.com/mb/2010/ai_charger/
But make sure to make a backup and restore from it in case something goes wrong.