Crystal Reports is a popular Windows-based report writer (report generation program) that allows a programmer to create reports from a variety of data sources with a minimum of written code. Crystal Reports is a popular Windows-based report writer (report generation program) that allows a programmer to create reports from a variety of data sources with a minimum of written code. WhatIs.com
What are DAT files? Virus definition or DAT files contain virus signatures and other information that McAfee anti-virus products use to protect your computer against existing and new potential threats. DAT files are released on a daily basis.
I would personally not pay for Mcafee, it causes a lot of problems with your system and can be a resource hog. If you do decide to use another anti-virus then remove Mcafee using this tool: http://download.mcafee.com/products/licensed/cust_support_patches/MCPR.exe.