Added note:

mIRC does not release patches. *IF* it does, which is hugely unlikely, then that news will always be posted on the front homepage. If nothing is there about patches, then it means the patch is not real.

If there is a patch for Windows XP then the only legitimate ones will be released by Microsoft. If that is the case, then you can go to Windows Update to find the latest updates for Windows XP, and critical updates.