How to charge iPad (v1) on a Windows device
Solution 1:
An insufficiently-powered USB port will charge an iPad, just slower than a high-powered one.
When you plug the USB cable into your laptop the iPad will say "Not Charging." However, when the screen is off it is in fact charging. As soon as you turn the screen on again the battery area will say "Not Charging," too, but again, with the screen off it will charge.
Test it yourself: before plugging in the cable check the battery percentage. Then plug it in and leave the iPad off for 30 minutes; when you turn the screen back on you'll see that the percentage has increased.
In my case it takes several hours to charge from 50% to 100%, but at least it's charging.
Solution 2:
If your iPad won't charge when connected to your Windows laptop, the most likely reason is because the USB port you are using doesn't provide enough power for the job.
MacBooks in the last several years are designed to provide sufficient power via USB, but I can't comment on your Windows machine. Sounds like that USB port you are using simply doesn't provide enough power to charge the iPad.
There's no real practical and easy "fix" for this on a laptop. See if the USB port outputs more power when you plug-in the laptop to the wall… though it's unlikely…
Sorry.