Here's the situation: Bought a new computer, installed XP with a disk from a laptop I'd bought in '04 but no longer have. The CD key was on a sticker that was on the laptop. Now I have no CD key and an XP that expires in 30 days. I see no way out of this except to buy another copy of Windows...which is the biggest bs I've ever seen, and something I wouldn't do even if I had the excess money to do it. Is there anything I can do about this?

There is no legal way to activate that XP installation, besides getting that sticker back. And if that XP is an OEM version (in case of laptops almost always), you're not even allowed to install it on another computer anyway.

So the only legal way out is to buy a new license, or to use a free OS, like Ubuntu.

installed XP with a disk from a laptop I'd bought in '04 but no longer have.

You said it, you don't have it anymore. No laptop, no license. Wether you sold it or lost it, ... it's gone.