Ok, before you read how to get it, here's my caveat: I have not installed it myself and probably will not for at least a couple of weeks after the consumer version is released; the information below should be considered to be for power users.
Here's where you can download the network installation package or you can download a version from here. This install is not really designed to simply update one machine, but you can update one machine should that be your end goal. If you are willing to wait for the consumer version of SP2, simply go to this link and follow the instructions; essentially it just turns on Automatic Updates for you and verifies your firewall and virus protection.
If you are looking to create a clean Windows XP install CD that includes the SP2 components, go to this link and follow the extensive instructions complete with screenshots. Note: You will need the following to accomplish this:
- Windows XP CD
- Windows XP SP2
- About 1.5GB of disk space free
- Nero Burning ROM (at least that's what the instructions are based on using)