By now you should be aware that Windows XP is a complete liability for your law firm. While support is over for XP and no security patches are being released it should be understood that antivirus signatures for XP are stopping as well. This means that even with your XP computer you will not be safe from viruses or spyware. These days any computer connected to the internet is at risk as well as the data on that computer.
Do yourself a favor and upgrade as soon as possible especially if your firm has Windows XP computers.