In theory yes. But if you have an ntfs filsystem (default for Win 2k and XP) it really isn't a good idea: you could effectively trash the whole filesystem if you try to do anything worthwhile.

If that's the case, best bet is to make sure the firewall is up, then upgrade or install AV software, then get the M$ patches.

Of course, if you have blaster (which seems to want to shut the Windows system down especially if you use IE) you could always use Knoppix and a flash drive to download solutions/patches.