Should I quit using my windows xp next week?

Don't worry about it. Microsoft is trying to scare people into buying Windows 8.

Everything should still work. And as long as you are somewhat careful about the software you install, you should not have a problem. It is true that it will be exposed to some security issues; but, the chance of them affecting you is next to nothing. Just have a good Anti-Virus software package installed (such as Avast - Free Edition) and run something like MalwareBytes - Free Edition every few weeks and you should have no problem.

You can use the computer for anything except connecting to the internet. Once you do that, viruses galore await you. Despite what you may read about other anti virus software providers taking over Microsoft's job of writing cures for viruses and updates for XP, that isn't going to happen. It's just to expensive, ( the reason Microsoft is leaving XP on its own ). Not enough users to make writing anti virus and updates worth their time and expense for a 13 year old operating system. Windows XP hung around longer than normal due to the poor acceptance of its successor, Windows Vista.

Anti-virus applications and firewalls will still run, and most vendors will still update them. No need for worry at this point in time. It is just that Microsoft has dropped updates for XP.