The soundcard isn't included in Windows Activation, you can change it every day for the next year and you'll never be asked to reactivate for that on its own.
The hard drive count for activation is only the first one that Windows finds. Therefore if you add a second drive, again you can change that until the cows come home and you'll never be prompted for reactivation on that on its own.
The only hardware that can trigger a reactivation in XP and Vista is as follows:
# Display Adapter
# SCSI Adapter
# IDE Adapter (effectively the motherboard)
# Network Adapter (NIC) and its MAC Address (this carries three points)
# RAM Amount Range (i.e., 0-64mb, 64-128mb, etc.)
# Processor Type
# Processor Serial Number
# Hard Drive Device
# Hard Drive Volume Serial Number (VSN)
# CD-ROM / CD-RW / DVD-ROM
These counts only apply to the
first seen product in that category. Therefore the first hard drive, the first CD unit and the first network card. Chopping and changing secondary drives makes no difference to an activation status. If you were to clone your old installation to the new drive and you've made other changes previously, then the new drive and the new volume serial number are enough on their own to want a new activation.
Also note that you can, for example, change the graphics card. It'll knock one off the activation tally of ten. However if you change the graphics card again, it does not knock another one off. Therefore if you activate with, for example, a Radeon X1600, then stick in an NVidia 8600GT, you'll lose one point. If you then stick in a Radeon HD3850, you won't lose another point. As long as you have a score of more than seven, you won't need to reactivate.
The network card carries three points. Disabling the onboard network LAN for the first time after an activation will almost always cause the system to want you to reactivate.
Details here:
http://www.aumha.org/win5/a/wpa.htm
Edited by Neil Jones, 28 December 2007 - 05:28 PM.