Actually you can, but it's using a workaround. If you look for the "Ultimate Boot CD for Windows" it's self-booting and has a Windows Setup option. You can use that to "Repair" your installation and put in a valid key. I'd suggest the earlier options I'd given you, an OEM key with an OEM disc for your system (if it's something like Gateway, Dell, Acer, Ibm/Lenovo, HP, etc) will let you get back up and running under Windows XP. But it'll likely be a reinstall from scratch, so back things up first.
Second option, Linux LiveCD.. again, I just downloadeed a Mepis disc and it let me access what I needed off my system. (Working on rebuilding a Windows 2000 box as well with corrupt registries and I'm using a Linux disc to copy backups around. Into Safe Mode with it now, but no networking or Normal mode yet). Mint is good as well. One thing I'd look for online to download if you go the Linux route is Winedoors, it's older but it does an awesome job of getting Windows apps running under Linux using Wine.
Another lesser option might be ReactOS, but I don't think that's ready for Prime Time yet. But you might get a LiveCD of it and use that for data backup.
If you do throw a Linux install on the box, make sure not to overwrite your current partition, most distros will squish the Windows partition a bit to give itself room on the hard drive. So choose that option, not to wipe or delete any existing partitions.
Absolute safest option? Pull the hard drive out and put it on a shelf. Go out and buy a drive enclosure and another hard drive for the computer. Put the original drive in the enclosure, install Windows on the replacement drive. Rebuild, then plug in the enclosure and copy data (not the full drive) back onto your new install. Then you also have a good backup of your ships and such sitting in an accessible enclosure and probably more room in your Windows install because you'll probably have a larger drive in the box. Win/win..
Good luck man..