I have a laptop and a desktop, both of which are currently inoperable, the laptop because it no longer charges, and the desktop because I took out the hard drive and somehow lost it. I was wondering if I could take out my laptop hard drive, put it in a USB drive casing and somehow boot it via USB on my desktop? The laptop drive is running Win XP. This is probably impossible but I thought I would ask in case anyone knows. Thanks!

I'm going to file it under the "not impossible, but extremely unlikely" category.

First, you'd have to have a desktop machine that's new enough to be able to boot off a USB device, then go into the BIOS and change the boot order so that USB is listed before CD/HDD.

Once that is done, you'd need to pray that Windows would actually load. Back in the Win98 days, if you swapped a hard drive like that, Windows would just flat out crash because it couldn't handle the massive change in hardware. I don't know if this is still the case in WinXP.

Good luck!

Windows XP after installed is hardware dependant.  Making a change here and there is one thing, but flat out throwing it into another machine will probably require a reinstallation.  Regardless, reinstall will take re-authentication of your OS.  So if your desktop had XP on it when you bought it (ie. an OEM version of XP), you're not so likely to get Microsoft's approval to install it again.

However, you could possibly try booting into Safe Mode if you had to recover data from the laptop hard drive or something.  But you'll need something else for a permanent solution.