The WPA system checks ten categories of hardware:
1. Display Adapter
2.SCSI Adapter
3.IDE Adapter (effectively the motherboard)
4.Network Adapter (NIC) and its MAC Address
5. RAM Amount Range (i.e., 0-64mb, 64-128mb, etc.)
6.Processor Type
7.Processor Serial Number
8.Hard Drive Device
9.Hard Drive Volume Serial Number (VSN)
10.CD-ROM / CD-RW / DVD-ROM
If your hardware is substantially the same, this will be done by an automated call without your needing to talk to anyone.
What does ‘substantially the same' mean? WPA asks for ‘votes' from each of these ten categories: ‘Is the same device still around, or has there never been one?' Seven Yes votes means all is well — and a NIC, present originally and not changed, counts for three yes votes! Minor cards, like sound cards, don't come into the mix at all. If you keep the motherboard, with the same amount of RAM and processor, and an always present cheap NIC (available for $10 or less), you can change everything else as much as you like.
If you change the device in any category, you have lost that Yes vote — but will not lose it any more thereafter if you make changes in that category again. So, for example, you can install a new video display card every month for as long as you like.